Majumder was raised in Burlington, Newfoundland and Labrador to Marian Bartlett, a European-Canadian woman from Newfoundland, and to Mani Majumder, a Bengali Hindu Indian man, originally from West Bengal. His parents split after seven years. Majumder has an older sister named Rani.
Majumder has said that because he was raised by a white mother and around white people, he had no idea he "was anything but white". In his standup acts, he jokes about joining his schoolmates in chanting racist slurs before realizing that he was the victim they were talking about. Majumder was very close to his mother who he says raised them selflessly so that he and his sister were unaware of the extreme poverty in which they lived. His mother died of a heart attack in 2003. Majumder feels a debt of love to Newfoundland which has influenced him and his work, and has given him a rhythm of appreciation for what he has.
He started his entertainment career as an announcer for the YTV game show CLIPS, and soon was hosting the network's popular morning kids show Brain Wash, where he was known as Ed Brainbin. He also hosted the "Slime Tour" segments on the popular game show Uh Oh!. Eventually he joined This Hour Has 22 Minutes in 2003, and also hosted 15 episodes of the Just for Laughs specials on television and participated in the Comedy festivals in Montreal. He was also a star of Cedric the Entertainer Presents, aired in the United States on the Fox network, and appeared in an NFB documentary on aspiring Canadian comics, The Next Big Thing.
Majumder has also starred in the CBC comedy pilot Hatching, Matching and Dispatching and the short film Plain Brown Rapper, as well as playing Kumar's brother in the 2004 comedy Harold & Kumar Go to White Castle.
Majumder often plays an alter ego called Raj Binder. Binder is an awkward, nervous and usually excessively sweaty Indian reporter with a strong accent. Binder first appeared in a sketch from a comedy showcase with some former YTV costars called The Bobroom, and also appeared on Just For Laughs and This Hour Has 22 Minutes. Majumder caused some minor controversy when "Raj" posed in the MegaStars group picture during the 2003 Heritage Classic NHL outdoor ice-hockey game.
Majumder made a guest appearance on two episodes of the television series 24, playing Hasan Numair. He also played Dr. Freddy Sahgal in the short-lived Fox TV series Unhitched, which aired in March 2008.
In 2010, he had a guest starring role as Benny Natchie in Republic of Doyle, and from 2010 to 2011 starred in the American TV series Detroit 1-8-7 as Detective Vikram Mahajan.
In the summer of 2011 Majumder was cast in The Firm, a Canadian-American co-production, in the recurring role of Andrew Palmer, the lawyer at the firm who befriends Josh Lucas' character Mitch McDeere. The show ran for one season.
From 2013 to 2014, Majumder starred in the documentary TV series Majumder Manor, which documented his quest to develop the tourism potential in his picturesque hometown of Burlington, Newfoundland. The show also featured his family, friends, and community.
In December 2016, Majumder starred in a controversial short produced by This Hour Has 22 Minutes, titled "Beige Power", which called for white supremacists to "embrace the beige" and accept that humans will all "look the same by the year 3000". The short received criticism from social media, particularly from the alt-right community.
On 21 December 2012, Majumder married American actress Shelby Fenner.