The ex-Celtic striker will jump from 15,000 feet to raise cash for a children's respite care home in East Renfrewshire.
Frank revealed his personal inspiration for tackling his life-long fear - his friend's 14-year-old daughter, Rebecca Withers.
The 54-year-old - known as Macca - said: "I've got a huge fear of heights but weirdly I've always wanted to skydive.
"I've done some crazy things in my time but this is ranking up there in the top five.
"I can't believe I'm actually going to launch myself out of a plane but it's for a great cause."
The nervous ex-Scotland player - famed for comedy expression 'where's the burdz' - said: "I hope, on this occasion, there aren't any birds about when I'm flying through the air. Knowing my luck one of them will hit me."
Rebecca has learning difficulties and Epilepsy and is a regular visitor to Chavey Down residential home.
The home, in Newton Mearns, is run by Quarriers UK and offers short-stay care to youngsters up to the age of 16.
The former striker added: "I've known Jack and Marie Withers a long time and their daughter, Rebecca is only 14 and suffers from severe epilepsy and has learning difficulties. I know from them how valuable a resource like Chavey Down is and wanted to do something to help raise money for it.
"Rebecca is a lovely girl and it's a pleasure to try and help."
Quarriers Community Fundraiser Kerry Reich said everyone was "over the moon" that McAvennie was taking part in the challenge.
The money raised will help buy much needed sensory equipment for the house and garden. To sponsor Frank, visit: www.justgiving.com/Frank-McAvennie1 or text FMSD 89 followed by £1, £2, £3, £5 or £10 to 70070.