The 39-year-old actor is reportedly engaged to Georgia Moffett – the actress daughter of fifth Time Lord Peter Davidson.
David and 26-year-old Georgia are apparently planning to wed on New Year's Day 2012.
The couple have been dating for two-and-a-half years, after meeting on the set of Doctor Who in 2008.
Georgia appeared in an espisode, playing the Doctor's daughter Jenny (pictured below).
When they wed, David will become stepfather to her eight-year-old son Tyler. Georgia had him when she was 17 and still at school.
The former Doctor has already been given the seal of approval by his fiancée's father.
Two years ago Georgia's dad Peter told the Daily Mail he was pleased about his daughter's new boyfriend.
"It's great because David is a genuinely nice guy - and also a very fine Doctor Who," he said.
"I'm delighted Georgia has found happiness because she hasn't always had an easy life."
Prior to settling down with Georgia, David was linked with second assistant director Jennie Fava and BBC Wales staff member, Bethan Britton.
In October 2007 the Scotland-born star split with Underworld actress Sophia Myles after a two-year relationship.
They also met on set - Sophia played Madame de Pompadour in Dr Who back in 2006.