Bromley’s free-scoring midfielder has earned a move to League One Gillingham.
Rees notched an impressive 16 goals in 41 games for the club last season - and that alerted the attention of the Gills.
Rees moves up after one year in the top tier of Non-League football having joined from Chelmsford City last July.
His manager Neil Smith thinks he will be a big success in the Football League.
“I am delighted for Josh, he has been a fantastic player for us this season and I am delighted that another Bromley player will be getting the chance to play League One football next season," Smith told the club's website.
He will be able to say a proper goodbye in a months’ time.
His new club travel to Hayes Lane for a pre-season friendly on Tuesday July 10.