Mansour was a major part of the Panthers for a long period of time, making his debut for the club in 2012 and playing for them until 2020, where he scored 74 tries in 158 games.
He then played a further 16 games for the South Sydney Rabbitohs, scoring another 12 tries.
Form and injuries hampered his progress through the back end of his stint in rugby league, with the now 33-year-old winger playing a large chunk of NSW Cup in recent years, including the 2023 season for the Newtown Jets, who are the feeder side of the Cronulla Sharks.
A power packet winger in his prime, Mansour played seven Tests for Australia (between 2014 and 2017) and three State of Origins for New South Wales (all in 2016), while he also scored five tries in seven Tests for Lebanon.
Mansour took to his Instagram to confirm the decision to hang up the boots.
"I just wanted to come on here today and share some important news with you all," Mansour said in the video.
"It's a decision that wasn't an easy one to make and has been weighing quite heavily on my chest, but I believe it's the right time to hang up the boots after an amazing 12 seasons and focus on the next stage of my life."
Mansour also wrote in the caption that he was thankful to those who had supported his career.
The winger promised to remain around rugby league despite not taking an active on-field role in seasons to come, with former teammates and rivals including Josh Addo-Carr, Nathan Peats, Beau Ryan, Mitch Rein, Nathan Cleary, James Fisher-Harris and Tyson Frizell among others taking to the comments section to pay their respect to his career.