The 21-year-old Scotland U19 and U21 international is a product of the Pittodrie youth system, and made his first Dons start against Rangers in May 2009.
Pawlett has suffered with several injuries in his short Pittodrie career, but has fully recovered this year.
However the skilful forward has never appeared to be part of manager Craig Brown's plans, appearing only as a substitute this season.
Craig Brown told RedWeb: "We have still got Megginson, we have still got Hayes, we have still got young Ryan Fraser who can all play out wide so to ensure Peter Pawlett gets game time we think loaning him to St Johnstone is a very acceptable arrangement.
"Hopefully the move and the chance to play regular football will return Peter to the form he was showing a couple of seasons ago.
"I still very much see Peter as a future Aberdeen player."