The 26-year old Brazilian-born Australian citizen, who will join Al-Ahli for a reported $2million, admitted it was a sad time to leave the Roar after joining back in 2005.
"Every moment I've had with Brisbane Roar was great," Reinaldo said.
"I've made a lot of friends here, my coach Ange (Postecoglou) and the staff - they looked after me all the time.
"Even when I was injured, they supported me a lot.
"It's a tough moment for me to leave my home and my friends but it's a great opportunity and I can't lose that because it's for the future of my family."
Postecoglou thanked Reinaldo for his contributions during his five year stint with the club, saying he was a tremendous Brisbane Roar ambassador both on and off the field.
"From our point of view, it's with mixed emotions that we watch the big fellow depart," Postecoglou said.
"In the last 12 months since I've taken over, he's played a key role in what we've tried to rebuild.
"He will always be welcome back here and hopefully he feels a part of what we're building here at the Roar.
"The way he's presented himself and the way he's represented the club, these are the type of things that don't come along too often."