"I am sorry to announce that I will be leaving London at the end of the season to return to Cumbria for family reasons," said Rob. "My decision has nothing to do with the club or the team it is purely for personal reasons.
"I would like to take this chance to thank all the supporters for their support over the last 10 years; the last couple have been particularly hard. I hope to see you all over the last few games of the season at The Stoop and these will be my last games for Harlequins RL."
Chairman David Hughes, paying tribute to Rob and his contributions to first London Broncos and then Harlequins RL, said: "He's been a fantastic servant for us and it's been a wonderful 10 years. It was a brave step to come down from Cumbria and set up home here.
"Rob's a super captain and a super character, I wish we had 13 like him. He's had some tough personal issues to deal with and been a bit unlucky with injuries, which he didn't deserve. But he's such a good kid and a fantastic guy; we wish him all the best. I hope he keeps in touch with the club."
Head Coach Rob Powell added: "It's sad to see Rob leave. He has been a massive player and leader for the club and his absence will leave a big void for the club to fill. We fully support his decision to move back to Cumbria and wish him and his wife Sarah all the best for the future."