The former Scotland international and Norwich City head coach will also aid Gemmill for the forthcoming 2019 UEFA European Under-21 Championship qualifying matches.
Scotland head to France later this month for the prestigious Toulon Tournament later this month where Scotland Under-20s will face in Czech Republic, Brazil and Indonesia in Group C before the under-21s begin their qualifying campaign with an opening match against Netherlands in September.
Grant, who played for Celtic, Norwich City, Reading and Bournemouth, has an abundance of coaching experience, working at West Ham United, Celtic and Birmingham City among others. He is currently lead development coach at Championship side Fulham.
“I was lucky enough to play for Scotland at youth level and for the senior squad and loved every minute of it so it is a great honour to be asked to help nurture the next generation of international players,” said Grant, who won two Scotland caps.
“I would like to thank Fulham for their support in allowing me to perform this role. I am looking forward to meeting up with Scot and the rest of the team later this month as we prepare for the Toulon Tournament.”
Scot Gemmill, national youth team coach, said: “Peter is a highly-respected coach and will provide us with great experience ahead of an exciting and challenging period for our young players. I am looking forward to working with him in the coming months.”
Gemmill will announce his Scotland U20 squad for this year’s Toulon Tournament at 1pm on Wednesday.