Tegan and Sara began playing guitar and writing songs at age 15, forming a band called Plunk without a drummer or bass player. In 1997, they used their school’s recording studio to record two demo albums: Who’s in Your Band? and Play Day. In 1998, they won Calgary’s “Garage Warz” competition, using the studio time they won to record their first professional demo under the name “Sara and Tegan”, Yellow tape, which was followed by Orange tape and Red tape. Their first “big-time show” was in May 1998 in Calgary, opening for Hayden.

Tegan and Sara began touring after graduating from high school in 1998, travelling by car or Greyhound bus. In 2000, they toured with Neil Young and the Pretenders. Other notable touring mates include Ryan Adams, Weezer, Bryan Adams, Jack Johnson, the Black Keys, Ben Folds, Gogol Bordello, Cake, City and Colour, Death Cab for Cutie, Hot Hot Heat, the Killers, New Found Glory, Paramore, Rufus Wainwright, Eugene Francis Jnr, the Jezabels, An Horse, Steel Train, Holly Miranda, and Speak.

In 1999, they released their debut album Under Feet Like Ours independently under the “Sara and Tegan” name with producer Jared Kuemper. Two songs from Red tape appeared on the album, and two from Orange tape. They later changed their name to “Tegan and Sara” because people thought they were a solo act named “Sara Antegan”. The new name was more memorable and their first album was later reprinted under the name Tegan and Sara. The same year, they signed with Neil Young’s Vapor Records and released This Business of Art through the label in 2000. They have toured extensively since then. In 2002, the band released their third album If It Was You. Their fourth album, So Jealous, was released in 2004 and led to wider success and attention, both locally and internationally. This album was released through both Vapor and Sanctuary. One track of the album, “Walking with a Ghost”, was covered by the White Stripes, who released it on their Walking with a Ghost EP.

In 2006, Tegan and Sara appeared in The L Word episode “Last Dance” (season 3, episode 11); they had a small role in which they played themselves performing their song “Love Type Thing” and exchanged a few lines with main character Dana Fairbanks. In 2008, they appeared on the kids’ music television show Pancake Mountain where they acted in a skit and performed their songs “Back in Your Head”, “Hop a Plane”, and an acoustic version of “Walking with a Ghost”. In 2010, they appeared on CBC’s Mamma Yamma, revising their single “Alligator” into a children’s song. In 2012, Tegan and Sara appeared in the 90210 episode “The Things We Do for Love” performing “Closer” and “Now I’m All Messed Up” from their album Heartthrob.

Their 2007 album, The Con, was released by Vapor and Sire because Sanctuary chose to no longer release new music in the United States. The album was co-produced by Chris Walla. Jason McGerr of Death Cab for Cutie, Matt Sharp of the Rentals, and previously Weezer, Hunter Burgan of AFI, and Kaki King all appeared and collaborated on the album.

Tegan appeared on Against Me!’s song “Borne of the FM Waves of the Heart”, and also appears in the music video. She also sang backing vocals on Rachael Cantu’s “Saturday” from her Run All Night. In April 2008, Tegan wrote and recorded a song titled “His Love” at the request of Augusten Burroughs as a contribution to the audio version of his book A Wolf at the Table. The two headlined Spin’s September 2008 Liner Notes benefit for Housing Works, a New York non-profit. Tegan sang with Jim Ward on his track “Broken Songs” and on the song “Contrails” by rapper Astronautalis which appeared on his 2011 album This Is Our Science. She also appeared in the music video. Tegan was also featured in one of the songs off of Dan Mangan’s new LP Unmake, titled “Forgetery Redux”. In 2017, Tegan was featured on Ria Mae’s album on the song “Broken”.

On October 26, 2009, Tegan and Sara released their sixth album Sainthood, produced by Chris Walla and Howard Redekopp. The duo also put out a three-volume book set titled ON, IN, AT, which is a collection of stories, essays, journals, and photos of the band on tour in America in the fall of 2008, writing together in New Orleans, and touring Australia. The photographs in the book are taken by Lindsey Byrnes and Ryan Russell. The album Sainthood debuted on the Billboard 200 chart at number 21 selling 24,000 copies in its first week. While recording Sainthood, Tegan and Sara spent a week writing songs together in New Orleans. The song “Paperback Head” was the only song written by the pair to appear on the album, making it the first song on any Tegan and Sara album that they wrote together. Spin magazine gave Sainthood four out of five stars and wrote, “Tegan and Sara’s music may no longer be the stuff of teens, but its strength remains in how much it feels like two people talking.”

In 2009, Tegan and Sara worked as producers for the first time. Tegan worked with char2d2 on the 2009 Small Vampires EP, while Sara worked on the 2010 debut albums for Fences and Hesta Prynn.

In 2011, they launched “2011: A Merch Odyssey”, which saw at least one new item in the official online stores every month, all year long. A live CD/DVD combination package titled Get Along was released on November 15 and contains three films titled “States”, “India”, and “For the Most Part”. Get Along was nominated in the 2013 Grammy Awards for Best Long Form Music Video.

Sara sings on the Reason’s song “We’re So Beyond This”, and also appears in the music video. She was featured on rapper/songwriter/producer Theophilus London’s track “Why Even Try” from his 2011 Lovers Holiday EP. Sara appears on Jonathan Coulton’s 2011 album Artificial Heart, providing vocals for the album’s remake of the song Coulton wrote for Valve’s game Portal, “Still Alive”. Sara covered Alicia Keys’ “Try Sleeping with a Broken Heart” from Doveman’s Burgundy Stain Sessions in 2011. In Kaki King’s music video for “Pull Me Out Alive”, Sara can be seen as well. Sara sang back-up vocals on two songs from former Smashing Pumpkins member James Iha’s 2012 album Look to the Sky: “To Who Knows Where” and “Dream Tonight”.

In 2011, Sara was a panellist on the CBC Radio One program Canada Reads, defending Jeff Lemire’s graphic novel Essex County. The book, the first graphic novel to be featured as part of Canada Reads, was voted off after the first round but then later placed No. 1 in a “People’s Choice” poll with more votes than all other books combined.

Tegan and Sara started recording their seventh studio album, Heartthrob, on February 20, 2012. Eight songs were produced by Greg Kurstin. Joey Waronker contributed drums to these songs. Two songs were produced by Mike Elizondo, with Victor Indrizzo contributing drums, Josh Lopez contributing guitar, and Dave Palmer contributing piano. The last two songs were produced by Justin Meldal-Johnsen. The first single, “Closer”, was released on September 25, 2012. The album was released on January 29, 2013 and debuted on the Billboard top 200 at number 3, the band’s highest charting record to date, selling 49,000 copies in its first week. Heartthrob debuted at number 2 on the Canadian chart, digital downloads chart and hit number 1 on the rock and alternative album charts. In July 2013, the album was shortlisted for the 2013 Polaris Music Prize. In March 2014, Tegan and Sara won three Juno Awards for Single of the Year, Pop Album of the Year, and Group of the Year.

In 2012, they appeared on the cover of Under the Radar magazine’s “Protest” issue. Both were photographed holding a sign that read “The rights of the minority should never be subject to the whim of the majority.” Also in Canada, they were actively supporting Quebec students in their protest against that provincial government. In the U.S., both were vocal during California’s Prop 8 debates. On November 10, 2016, rather than boycotting North Carolina for HB2, Tegan and Sara performed at The Orange Peel and donated their proceeds to Equality North Carolina in order to fight the legislation. This inspired the band Matt and Kim to match their donation in the form of merchandise proceeds.

In 2013, the band partnered with Coolhaus, their “favourite ice cream sandwich truck”, to create an ice cream sandwich in favour of marriage equality. The sandwich featured Double Chocolate cookies and Salted Caramel ice cream, and was named “Til Death Do Us Part”.

In 2013, Tegan and Sara opened for the band fun. on their Most Nights Summer Tour which started in Toronto, Ontario on July 6 and ended in Bridgeport, Connecticut on September 28.

In March 2013 during the SXSW festival, Tegan and Sara co-hosted the MTVU Woodie Awards with rapper Machine Gun Kelly. They also performed their single “Closer”. The Woodie Awards aired on MTV on March 17, 2013. On September 30, 2013, Tegan and Sara performed “Closer” on Today.

Due to the expansion of their audience they have gained a higher profile in the LGBTQ community. They were awarded Outstanding Music Artist at the GLAAD Media Awards, beating out high-profile musicians including Lady Gaga and Elton John. In June 2014, Tegan and Sara joined WorldPride to perform in the closing ceremonies at Yonge–Dundas Square in downtown Toronto.

They have performed at festivals including the Mariposa Folk Festival 2001, Sarah McLachlan’s Lilith Fair 1999, 2010, Coachella 2005, 2008, 2013 Lollapalooza, SXSW 2005, 2013, Austin City Limits, Bonnaroo, Falls Festival, Sasquatch! 2010, Osheaga, Cyndi Lauper’s True Colors Tour 2008; Southbound 2009, Glastonbury 2010, Lilith Fair, Australia’s Groovin’ the Moo 2010 and 2013, Splendour in the Grass 2016, Winnipeg Folk Festival 2011, Newport Folk Festival 2011, askTel Saskatchewan Jazz Festival 2011, Cisco Ottawa Bluesfest 2011 and 2015, Outside Lands 2014, and Firefly 2014. They performed at the ending ceremony in June at Toronto World Pride 2014 and also at Boston Calling in May 2014.

In January 2014, Katy Perry announced that Tegan and Sara, along with Capital Cities and Kacey Musgraves would be the opening acts for the North American leg of her Prismatic World Tour. Tegan and Sara toured with Perry from September to October 2014.

On February 25, 2014, Tegan and Sara announced their Let’s Make Things Physical Tour. The tour included a range of supporting acts for different cities, including Lucius, the Courtneys, Waters, and My Midnight Heart. The tour kicked off on 6 May in Columbia, Missouri, ending in November 2014.

In July 2014, the pair opened for Lady Gaga’s 2014 concert tour, ArtRave: The Artpop Ball Tour in Quebec City in front of a crowd of 80,000.

In early 2014, Tegan and Sara collaborated with the Lonely Island on a song called “Everything Is Awesome!!!” for The Lego Movie soundtrack. The movie opened in theatres on February 7, 2014. The song debuted at number 62 on the Billboard Hot 100 chart and number 24 on the Official UK Singles Chart. Chief songwriter/producer Shawn Patterson received an Oscar nomination for Best Original Song at the 87th Annual Academy Awards, losing to “Glory” by John Legend and Common, from the movie Selma.

Tegan and Sara finished their eighth studio album on November 30, 2015. On March 10, 2016, the band announced via their Facebook account that the album’s title would be Love You to Death, with the release date set for June 3. They released the lead single from the album, “Boyfriend”, on April 8. On April 25, tour dates were announced for their 2016 worldwide tour for the Love You to Death album. The duo released a music video for each track on the album. For the tenth anniversary of the release of their album The Con, Tegan and Sara collaborated with 17 artists including Cyndi Lauper to create The Con X: Covers in 2017. The participating artists created covers of The Con’s original songs which created a cohesive album sold to benefit the Tegan and Sara Foundation. Tegan and Sara also toured an acoustic version of The Con in 2017 with a portion of the proceeds supporting the Tegan and Sara Foundation.

In 2015, the sisters weren’t touring, taking time off to write and record their eighth studio album Love You to Death, which was officially released on June 3, 2016.

In December 2016, and in the wake of the United States’ presidential election, they founded the Tegan and Sara Foundation, to fight for “economic justice, health and representation for LGBTQ girls and women”. They have since partnered with Kiehl’s cosmetics to release Ultra Facial cleansers with limited edition packaging in order to raise funds for the foundation. Profits from The Con X: Covers and a portion of ticket prices from The Con’s tenth anniversary tour went to the Tegan and Sara Foundation. At the end of The Con 10th anniversary tour in 2017, they stated they plan to take two years off from touring to focus on the Tegan and Sara Foundation and to make a new record.

On April 25, 2016, their worldwide 2016 tour in support of Love You to Death was announced. The tour will start on June 22 in London, UK, passing through Australia, Hong Kong, Singapore, and Taiwan in July, and traveling across Canada and the United States starting September 9 in Saskatoon and wrapping up in Fort Lauderdale on November 16.

Tegan and Sara songs have been featured in the films Dallas Buyers Club, The Lego Movie, G.B.F., Monster-in-Law, Sweet November, These Girls, and The Carmilla Movie, and in the television shows Degrassi: The Next Generation, 90210, Being Erica, Ghost Whisperer, Grey’s Anatomy, The Hills, Hollyoaks, jPod, The L Word, Life Unexpected, Melrose Place, One Tree Hill, Parenthood, Rookie Blue, The Vampire Diaries, Veronica Mars, Waterloo Road, What’s New, Scooby-Doo?, Awkward, Riverdale, Girls, and BoJack Horseman. Their song “Closer” was covered by Glee on the episode “Feud” which aired March 14, 2013 at 9 pm EST on Global for Canada and Fox for USA. The song is also used in the teaser trailer for the 2013 independent comedy film, Exes. The songs “Closer” and “Back in Your Head” were featured in the 2016 video game LOUD on Planet X.

In September 2017, Tegan appeared as a guest on Cameron Esposito’s podcast, Queery. In October 2017, Sara was a guest on the show. In October 2019, both sisters appeared together on the podcast.

On December 11, 2018, Tegan and Sara announced a memoir entitled High School, sharing the story of their youth, to be released fall 2019, along with new music.

In May 2018 at Out Web Fest, Tegan stated they are working on a book, podcast, and new record.

In early 2019, Tegan and Sara announced they were working on their next record for release later that year. On July 9, 2019, they announced via Instagram that their ninth album is called Hey, I’m Just Like You, and consists of twelve rerecorded songs they initially wrote as teenagers. It was released on September 27, 2019, three days after the release of their memoir, High School.

Their memoir, High School, was published on September 24, 2019 by MCD Books, a division of Farrar, Straus and Giroux, alongside Simon & Schuster Canada and Virago Press in the United Kingdom.

In April 2020, the duo created a live “show” that they named Where Does the Good Grow, to entertain their fans during the COVID-19 pandemic. On May 12, 2020, they announced that they were releasing merchandise designed by EE Storey for Where Does the Good Grow. The show was held every Thursday at 3PM PST on their Instagram account, until the series finale on 23rd July 2020.