Ohanian was born in Brooklyn, New York, to a German mother, Anke (née Prigge), and an Armenian father, Chris Ohanian. His grandparents came to the US as refugees after the Armenian Genocide. Alexis went to Howard High School in Ellicott City, Maryland, where he gave the student address for his graduating class in 2001.

After graduating from the University of Virginia in 2005 with degrees in commerce and history, Ohanian and friend Steve Huffman pitched the idea MyMobileMenu to Y Combinator. The company passed on the idea, but encouraged the duo to come up with another idea it could potentially fund. They subsequently came up with reddit.com with the goal of it becoming the “front page of the Internet.”.

Reddit joined Y-Combinator’s first batch of start-ups in the summer of 2005 and was later acquired by Condé Nast in 2006 for an undisclosed amount between $10–20 million. Ohanian continued to work closely with Reddit as a member of its board of directors. He returned to Reddit full-time with co-founder Huffman in July 2015 to lead the now-independent company. He stepped back from the company in February 2018 to return to focusing on investing.

In 2007, Ohanian launched Breadpig, an “uncorporation” that produces geeky merchandise and gives the proceeds to charity. He is no longer involved in the day-to-day operations of Breadpig.

In 2009, Ohanian spoke at TED about a whale named Mister Splashy Pants. After leaving Reddit in 2010, Ohanian spent three months working in microfinance as a Kiva fellow in Yerevan, Armenia. Ohanian helped launch travel search website Hipmunk in 2010, and now acts as an adviser. In June 2010, Ohanian announced the launch of his company Das Kapital Capital, which focuses on startup investing, advising and consulting.

Ohanian co-founded Initialized Capital in 2010 and made seed investments in startups including Instacart, Zenefits, Opendoor, and Cruise. It has had three funds, totaling over $500 million under management. In 2014, CB Insights analyzed all the investors in tech, ranking Ohanian number one for network centrality, the breadth of connections an investor has with other investors in the ecosystem and the quality and depth of those links.

In late 2010 and early 2011, Ohanian spoke out against Congress’s Stop Online Piracy Act and the Senate’s PROTECT IP Act. He helped lead the Internet-enabled campaign that eventually overturned the two bills. Ohanian spoke to members of Congress, helped launch the national anti-SOPA/PIPA protests that took place on January 18, 2012, and spoke at the rally in New York that was organized by NY Tech Meetup.

In 2011 and 2012, Ohanian was named to the Forbes “30 Under 30” list as an important figure in the technology industry. In 2013, Ohanian and Erik Martin were featured as “champions of innovation” in the 20th Anniversary issue of Wired. In 2015, Ohanian was named to the Crain’s “40 Under 40” list for business. In 2016, Ohanian was named one of Fast Company’s “Most Creative People in Business.”

In October 2012, Ohanian teamed up with Reddit General Manager Erik Martin and embarked on the Internet 2012 Bus Tour from Denver, Colorado, to Danville, Kentucky, to campaign for the open Internet during the Presidential and Vice Presidential debates. One of the campaign stops spurred the idea for a possible “National Geek Day” in Washington D.C.

On December 10, 2012, Ohanian teamed up with Lester Chambers of The Chambers Brothers to launch a Kickstarter project, with the intent to make a new album entitled “Lester’s Time Has Come.” According to Fast Company, Ohanian aimed “to prove that there are new, sustainable funding opportunities for artists now thanks to platforms like Kickstarter.” This project raised over $61,000 for Chambers.

Ohanian published a book entitled Without Their Permission: How the 21st Century Will Be Made, Not Managed on October 1, 2013. Without Their Permission ranked fourth on The Wall Street Journal’s best sellers list for Hardcover Business. In connection with the book, Ohanian embarked on a five-month, 150-stop and 75-university tour to promote the book.

In May 2014, Ohanian began lobbying the FCC to support net neutrality, culminating with a day-long phone-a-thon into the FCC and Congress on January 15, 2015.

Two years later, Ohanian raised $12,244 for the non-profit Black Girls Code on Tilt.com. In May 2014, Ohanian used Tilt.com again to launch “Save Net Neutrality: Billboard in FCC’s Backyard,” a crowdfunding campaign to protest the FCC’s plans to eliminate the idea of net neutrality.

In the summer of 2013, Small Empires with Alexis Ohanian, a weekly online series focused on rising startups in New York City hosted by Ohanian, premiered on The Verge. The first season ran for nine episodes. The second season premiered in October 2014.

On October 15, 2014, Ohanian launched the NYRD Radio podcast. Guests on the show have included Tim Ferriss, James Altucher, Carter Cleveland (founder of Artsy) and Cameron Russell. The podcast features a segment called Office Hours, in which aspiring entrepreneurs can apply to work through an idea with him.

On July 2, 2015, Reddit fired communications director Victoria Taylor, an administrator who coordinated celebrity interviews from Reddit’s New York office. In protest, volunteer moderators of the IAmA community set their forum to private, effectively turning it off, and other volunteer moderators followed suit because of “anger at the way the company routinely demands that the volunteers and community accept major changes that reduce [their] efficiency and increase [their] workload.” The following day, a moderator of IAmA posted that “Chooter (Victoria) was let go as an admin by u/kn0thing [Alexis Ohanian],” an assertion that was not widely reported on. Media outlets such as Variety blamed interim CEO Ellen Pao for the dismissal. Harassment, which was already being directed toward Pao in relation to other controversies, intensified and she resigned a week later. However, on July 12, former CEO Yishan Wong informed the Reddit community that Taylor was fired by “the CEO’s boss” and accused Ohanian of scapegoating. In the aftermath of Pao’s resignation, Ohanian elaborated on his role in Taylor’s dismissal. countering that, even though the AMA/IAmA changes came from him, he still reported to Pao. As was done for Pao, a petition was uploaded by Ivy Lee to Change.org asking Ohanian to step down, which collected 1,633 signatures. In 2017, Pao criticized Ohanian for avoiding the fallout by attending Wimbledon in the days immediately following Taylor’s firing.

Visiting Armenia on the occasion of the 100th anniversary of the Armenian Genocide, in April 2015, Reddit co-founder Alexis Ohanian toured Children of Armenia Fund (COAF)-supported villages in rural Armenia.

On January 8, 2015, Ohanian released the first episode – listed as “Episode 0” – of Reddit’s new podcast Upvoted, in which Ohanian delves deeper into real stories found on Reddit and talks to the users involved. Each week, the podcast focuses on a different story and features a guest around whom that story is centered.

Ohanian was named the “Ambassador to the East” for the early-stage venture firm Y Combinator. In this position, he meets with East Coast applicants, mentors New York YC founders, and is a general representative for the company. He also held the role of part-time partner and full-time partner at Y Combinator, before leaving in 2016 to help launch the third Initialized Capital fund with Garry Tan.

On December 29, 2016, Ohanian became engaged to tennis player Serena Williams. Their daughter, Alexis Olympia Ohanian, was born on September 1, 2017, in West Palm Beach, Florida. Ohanian and Williams married on November 16, 2017, in New Orleans. Ohanian has said “watching Williams compete has changed how he measures success in business.” Ohanian and Williams gave their daughter a doll, called Qai Qai, which has become famous on social media.

In early 2017, he worked with teenager Rayouf Alhumedhi to campaign for a hijab emoji. Ohanian helped arrange an AMA for Alhumedhi on r/twoxchromosomes about her idea and responded to critics. On July 17, 2017, Apple released its version of the hijab emoji.

Through Initialized Capital, Ohanian invested $3 million in childcare startup Kinside in 2019. In 2020, Ohanian also invested $4 million in Dispo (David’s Disposable).

Following the birth of his daughter, Ohanian became an advocate of paternity leave and wrote an article about his experience following his daughter’s birth in the New York Times. “After my wife nearly died giving birth, I spent months at home caring for my family”. In June 2019, Ohanian announced his plans to bring the pledge to lawmakers on Capitol Hill in late 2019 in a push to pass federal paid family leave legislation. He stated that “I hope to be meeting with many senators, representatives, plenty of dads, on both sides of the aisle, in both houses of the Legislature, who want this to be the law of the land.”

On June 5, 2020, Ohanian resigned from Reddit’s board, asking to be replaced by a black candidate in response to the killing of George Floyd. On June 10, 2020, it was announced that Michael Seibel, an African-American entrepreneur, was named a Reddit board member.

On July 21, 2020, Ohanian was announced as the lead investor in a primarily female group that was awarded a new franchise in the National Women’s Soccer League, the top level of the sport for women in the U.S. The new team, later unveiled as Angel City FC, is set to start play in 2022. The ownership group, in which women hold a majority interest, includes 14 former members of the U.S. women’s national team, Oscar-winning actress Natalie Portman, and numerous other prominent actresses, entertainers, media personalities, and sportspeople, among them Ohanian’s wife Serena Williams.

On May 21, 2020, Ohanian delivered the Commencement address for The Johns Hopkins University Class of 2020. Other notable guest speakers during the virtual ceremony included philanthropist and former New York City Mayor Michael R. Bloomberg; Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases and a leading member of the White House Coronavirus Task Force; and senior class president Pavan Patel.