When the sides met back in 2004 they played out an incredible Champions League tie, with Gerrard scoring a stunning late goal to help his side come from behind and beat the then Greek Champions.
Liverpool famously went on to win the Champions League that year in a remarkable final against AC Milan, with the England midfielder scoring the first of three second-half goals in another great Reds comeback.
The fixture is obviously held in high regard by Gerrard, who himself invited the Greek outfit to be the opposition for the testimonial match.
"I am delighted to be honoured by Liverpool FC with a testimonial match and particularly thrilled that Olympiacos have accepted my invitation to play the fixture," said the England captain on Liverpool's club website.
"Last time we met proved to be such a memorable game both for me personally and Liverpool Football Club."
Money raised by the testimonial match will be donated to the Steven Gerrard Foundation, which is dedicated to helping disadvantaged children.
The Reds skipper is delighted the match is going ahead and is particularly honoured by the part the Greek side will play in the occasion.
"I am also especially grateful that Olympiacos have truly embraced the aim of this match and chosen to donate their fee to charity. I am looking forward to what I know will be a fantastic game and a wonderful occasion," he added.
Gerrard, who has played for Liverpool over 600 times, made his Liverpool first-team debut back in 1998 against Blackburn Rovers.
He was made captain in 2003 and has scored 159 goals during his time with the Anfield outfit.