Left back Lewis Kinsella will be with the U's again for the 2017/18 season.
The U's had an option in his current contract, due to expire on June 30th, that enabled him to stay for another year, and have taken up that option.
Left back Kinsella joined the U's after being released by Aston Villa in the summer of 2016, but came through Arsenal's Academy before that.
The Watford born defender started last season in the U's side, and made over a dozen appearances before suffering a serious ankle injury that required surgery.
He was out of action for four months but fought his way back into the squad for the finale of the season, as the U's just missed out on a Play-Off place.