Following on from an earlier Deadline report, The Sun claimed that the actor would appear in the comedy, which focuses on the life of Harry Potter actor Warwick Davies.
"Johnny will guest star in Ricky's new BBC Two show," a source told the paper. "He's trying to work out his schedule but it will definitely go ahead.
"Johnny is a huge fan of Ricky's and has a great sense of humour. He has wanted to work with Ricky for ages and this is it."
Writing on his official website, Gervais addressed reports that both Depp and Jerry Seinfeld would appear in the series.
"The Depp bit is true. The Seinfeld bit isn't," he told fans.
Life's Too Short, which is expected to air on HBO in the US, begins filming in May.
It was recently confirmed that Gervais will reprise his role as David Brent in the series finale of the American version of The Office.