The Australian World Cup winner captained Oxford in his final competitive match but could not prevent the Dark Blues from sliding to a 22-16 defeat.
Cambridge secured their third straight victory with a powerful second-half performance as they hit back from 16-8 down with a destructive forwards display.
For Roff, the final whistle signalled the end of a career which included 86 Tests for Australia and three World Cups, including a winners' medal in 1999.
"We didn't get the result we were after but I said to them after that I wouldn't swap having played with them this season for anything," said Roff.
"I have been a very fortunate rugby player. We don't all get a Martin Johnson fairytale ending but I have been part of some very good sides.
"And I have a great sense of pride from having led one of the great clubs in world rugby."
Cambridge's forward pack proved the difference with former Wasps prop Jon Dawson scoring the opening try inside three minutes from a powerful lineout drive.
After ex-Leicester fly-half Ross Broadfoot had landed a penalty, Oxford hit back with an excellent score from full-back Chris Mahoney.
Oxford's former Australia Under-19 fly-half Craig McMahan landed two drop goals, a penalty and conversion to open the Dark Blues a 16-8 lead.
But Cambridge came again and tries from replacement flanker Thomas Malaney and number eight James Lumby earned a lead they refused to relinquish under great pressure in the closing minutes.
The sessions with Wasps head coach Shaun Edwards paid off as Cambridge held firm on their own line to retain the Lehmann Brothers trophy.
"Shaun Edwards is our secret weapon," said Cambridge director of rugby Tony Rodgers.
"The boys love him coming up. He is a complete nutter but he is a fantastic defence coach.
"The techniques he has taught these guys in three or four sessions over the last term came into fruition in the last eight minutes.
"He loves coming up to Cambridge and he is outstanding. I cannot speak highly enough of him.
"I think England should look at him without a doubt but they will probably lose him to Wales if they are not careful."