The 25-year-old New Zealander is one of four Connacht squad members to have played in all 13 games so far this season, including the recent Heineken Cup back-to-back fixtures against Toulouse.
Ah You joined Connacht in 2010, coming from Canterbury (NPC). Growing up in Christchurch and attending Christchurch Boys High, the former boxer switched to playing rugby full-time when he was 16-years-old.
Five years later, he caught the attention of Connacht while playing for New Zealand's juniors and soon made the move to the west of Ireland.
He has been capped by the All Blacks at Under-19 and Under-20 levels and was also a member of New Zealand's IRB Junior World Championship-winning sides in both 2007 and 2008.
Over the last three-and-a-half seasons with Connacht, Ah You has notched up 57 senior caps.
Welcoming the news, Connacht head coach Pat Lam said: "When I arrived here at the end of last season, we gave Rodney a one-year extension to prove to us that he has the ability to fulfil his obvious potential.
"With his performances this season and the progress and development he has made physically and mentally, his determination to succeed is more than evident.
"We are now delighted that he has signed a new contract which will secure him to Connacht for two more seasons. As a young prop who can play loosehead or tighthead and a good team man, Rodney will be a huge asset for Connacht Rugby and we look forward to seeing him develop further."
Ah You commented: "I'm thankful for another opportunity to continue my rugby here in Connacht. I believe we have a great future ahead of us and I'm excited to be a part of what's to come."