Cassidy will sign a two-year contract with Oldham on 1st July, following his release from Sky Bet Championship outfit Wolverhampton Wanderers.
And the striker, who spent the first half of last season on loan at Notts County and the second with Southend United, is already eager to get started at the Sky Bet League 1 outfit.
"I'm delighted to get things finalised as it's been in the pipeline for quite a while. I'm now looking forward to the opportunity,” the 22-year-old told the Latics’ official site.
"I'll bring hard work, good football and goals to the team. It's been a difficult couple of years for me and I want to get some confidence back and enjoy football again.
"The manager is full of enthusiasm and has told me what he expects from me next season. When he spoke to me, I instantly thought I want to play for this manager as he can bring confidence back into my game and then get the best out of me."
Cassidy is Darren Kelly’s third signing of the summer, and the 35-year-old manager is pleased to have added a player of such quality to his team.
"Jake is different to what we have got. The supporters know the strikers we have and Jake offers something different,” Kelly said.
"He is a finisher, has a very good physical presence and can hold up the play and link with the midfield so we are delighted he has joined.”