Bell previously worked as a channel executive across BBC2 and BBC4, during which time he was the executive lead on BBC2's Summer of British Film season as well as The Edwardians, Pop on Trial, The Lost Decade and Science Fiction Britannia on BBC4.
He takes up the new role with immediate effect, reporting to head of the factual indie commissioning team, Richard Klein.
"Mark is a passionate advocate for the BBC's factual output and brings a wealth of experience to the role,” Klein said. “I'm sure he will be a great force in harnessing the creative talent of the independent sector."
Bell added: "I am really looking forward to finding the best ways of making great content that will be found by as many people as possible. This means looking for fresh approaches to the communication of knowledge, making the intelligent accessible and the accessible intelligent."
Bell beat off competition for the role from former Five factual commissioning editor Alex Sutherland, Sky One factual commissioning editor Andrew O'Connell, and freelance factual producer/director Mark Westcott.
The appointment completes the indie commissioning team in factual. The features and factual formats position still remains vacant in the in-house commissioning team under Emma Swain.