MacIntosh's big break in television when he was cast as the deadpan accountant Keith Bishop in The Office. Besides The Office, MacIntosh has also appeared on various shows such as Miranda and Little Britain. He formed a double act with Tim FitzHigham and they performed at the Edinburgh Fringe Festival in 2007. In 2009, MacIntosh appeared alongside several other celebrities in a charity music video for the Chris Rea song "Driving Home for Christmas". In early 2013, he prepared to play at a new West End show Geek, A New Musical at the Tristan Bates Theatre, which opened on 22 April 2013. He is also a regular on the radio sitcom Cabin Pressure, as Carl, the bored ATC operator. In 2013 he appeared in a national TV advert for ao.com. A year later he appeared as Barry the window cleaner in the film The Confusion of Tongues (2014).
In 2016, MacIntosh will appear as Lionel in British romantic comedy film Finding Fatimah.
