The BPG Awards are decided by journalists who specialise in covering television, radio and the media.
Gatwa's character, who is gay, comes from a religious Ghanaian family, and is the best friend of central character Otis.
Below is some of his highlights from the first series of the comedy:
Elsewhere in the awards...
The Graham Norton Show picked up the award for best TV entertainment show, ahead of other shortlisted programmes Michael McIntyre's Big Show, Mortimer & Whitehouse: Gone Fishing, RuPaul's Drag Race UK and Taskmaster.
The awards were announced at a ceremony at Banking Hall in the City of London this lunchtime (13th March).
Elsewhere in the winners list, the TV dramas The Virtues and Chernobyl were handed prizes, and newsreader Moira Stuart received the Harvey Lee Award for an Outstanding Contribution to Broadcasting.
Jake Kanter, BPG Chair, comments: "I'm proud to say that, for the second year in a row, a record number of votes were cast for the Broadcasting Press Guild Awards, which is testament to the enduring qualities of the BPG and the continued vibrancy of British television. Congratulations to all the winners."
More details on the awards can be seen at broadcastingpressguild.org
For updates, click the button below.