Mamma Mia! Here We Go Again will premiere on BBC One as part of Red Nose Day 2019, on Friday 15th March.
The new sketch follows on ten years from Saunders' last spoof of the musical.
The BBC confirms: "Written by Jennifer Saunders as a tribute to last summer's box office smash hit, Mamma Mia Here We Go Yet Again! will see some of the UK's biggest names in acting and comedy recreating memorable moments from the sequel and even attempting to sing some of Abba's most iconic songs."
The BBC adds: "The sketch will see some familiar faces reprising their roles, with Jennifer Saunders playing Meryl Streep's Donna, Alan Carr playing Colin Firth's Harry and Philip Glenister playing Pierce Brosnan's Sam."
Jennifer Saunders says: "If I could have lived on the fake Mamma Mia set for the last year, I would have been very happy. So I am very, very, very happy to be back. This is undoubtedly one of the silliest things I've done. But my god I enjoy it so much."
Mamma Mia Here We Go Yet Again! will be screened on BBC One on Friday 15th March as part of Red Nose Day.
Comic Relief will also feature a sketch starring Bodyguard actor Richard Madden and the Four Weddings And A Funeral cast reuniting for a short sequel. Further highlights are due to be revealed in due course.
Here is the original Comic Relief spoof of Mamma Mia!, first shown in 2009:
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