In 1996 he appeared as a subject in Simon Target’s documentary Uni about three students studying at the University of Sydney (Hansen later satirised Target in CNNNN where he played the network’s British correspondent who was also called Simon Target). Soon-to-be fellow Chaser member Charles Firth was one of the other two students featured, with Craig Reucassel also making occasional background appearances. During the documentary it was revealed that Hansen suffered from clinical depression while attending the university.

Hansen was the guitarist and one of the vocalists for independent Sydney band The Fantastic Leslie. The Fantastic Leslie was composed of Cameron Bruce, Tom Gleeson, James Fletcher and Hansen. In July 1999 the band released their 6-track EP A Tiny Mark which was distributed through MGM Distribution. He was also a member of independent alternative band Mending.

Hansen co-wrote and appeared in the live show Cirque du Chaser, which toured Australia in 2005.

Hansen co-wrote the short film Garbage Man with Charles Firth and British comedian Henry Naylor. It was a Tropfest finalist in 2005 and a prizewinner at Germany’s Ohne Kohle festival. Hansen has also been known to feature on the musical comedy circuit, including a recorded performance of one of his more famous songs, ‘I Wish I Was A Scottish Stand-Up Comedian’, for the Laugh-A-Poolooza 2006 DVD release.

The most controversial song that Hansen has performed was The Eulogy Song, which was originally written for Chris Taylor’s play Dead Caesar, with music by Hansen and lyrics by Taylor. On 17 October 2007 episode of The War, Hansen performed the song which satirised the lives of several deceased celebrities, including Peter Brock, Stan Zemanek, Princess Diana, Donald Bradman, Steve Irwin, John Lennon, Jeff Buckley and Kerry Packer, expressing the view that people with flaws during life are often disproportionately hailed as “top blokes” after death. The song became the target of significant media attention, with several radio and television personalities saying the song was in “bad taste”, and both the then Prime Minister of Australia John Howard and then Leader of the Opposition Kevin Rudd expressing negative views.

Hansen has had writer/performer contributions to the Nine Network’s Comedy Inc. and the ABC’s My Favourite Album. He has performed occasional voice-overs for ABC programs including First Tuesday Book Club and Media Watch. He composed the music for Nickelodeon’s Sarvo and Napman, and songs for the Sesame Street character Ollie. Hansen appeared and presented at the 2007 MTV Australia Awards and the 2007 and 2011 ARIA Music Awards. In 2007, he made a guest appearance on Nine’s The Nation. In 2008, he appeared in a sketch on SBS’s Newstopia, as well as an episode of the Australian gaming TV show Good Game on the ABC, challenging the hosts to a ‘Roffle Cup’. He also made an appearance as a guest host on the program in 2010, filling in for host Steven O’Donnell, again in 2011 filling in for host Stephanie Bendixsen and 2012 filling in for O’Donnell. He also made an appearance as a special guest in Good Game 10th year birthday special in 2016. In 2009, he made guest appearances on Network Ten’s Rove and Good News Week. He appeared again on Good News Week in 2010, this time with Chris Taylor, in the guise of characters from their radio show The Blow Parade. The same year, he was a guest on Top Gear Australia, where he drove deliberately slowly around the celebrity track for humorous effect. With Chris Taylor, he co-hosted the Australian Commercial Radio Awards four times (2016-2019). In 2020 he was a guest on Whovians.

In 2008, Hansen toured Australia with The Chaser’s second stage show, The Chaser’s Age of Terror Variety Hour.

In October 2009, Hansen hosted The Goodies: Before, During and After, a live show by British comedy trio The Goodies at Sydney’s Riverside Theatre (Parramatta) and at the World’s Funniest Island comedy festival. The show involved Hansen interviewing Tim Brooke-Taylor and Graeme Garden, as well as performing a Goodies song with them.

Hansen composed the music for and starred in The Blow Parade, a scripted radio comedy series he made with Chris Taylor. It premiered on triple j on 28 April 2010. The series was released on CD and through the iTunes Store with bonus tracks. This album won the 2010 ARIA Award for Best Comedy Release.

Hansen was the host of Strictly Speaking, a speechmaking competition series, which aired on ABC1 in 2010.

In 2011, Hansen joined various combinations of The Chaser team’s members for a series of live shows in Sydney entitled The Chaser’s Empty Vessel.

He played the character ‘Dex’ in the 3D movie Sanctum, produced by Andrew Wight and released in 2011.

He was a producer and regular panellist on the comedy show The Unbelievable Truth, a TV version of the BBC Radio 4 program of the same name. It aired on Australia’s Seven Network in 2012.

In 2014, Hansen and Chris Taylor toured Australia with a revue show of new songs and sketches entitled One Man Show. In 2015, they toured In Conversation with Lionel Corn, a parody of writers festival sessions.

In 2017, Hansen co-starred in a production of the play Neville’s Island by Tim Firth at Sydney’s Ensemble Theatre, playing ‘Roy’.

Hansen has worked with Benjamin Maio Mackay twice, once on stage in 2016’s Great Detectives of Old Time Radio Live and again in 2017 as a supporting role in the audio drama adaptation of The Phoenix Files.

Hansen performed an updated version of The Eulogy Song in his 2020 tour.

Hansen co-presented Radio Chaser, a daily comedy show on Triple M, throughout 2017–19. The show spawned an album of 100 sketches, released in 2020.

In 2020, Hansen began touring Solo Show, a set of sketches and songs about people going it alone, performed on guitar, piano and iPad. He presented the show in Adelaide and Brisbane before postponing the remaining dates due to the COVID-19 pandemic.