The shrewd signing from Fulham settled quickly at Old Trafford and emerged as a reliable understudy to Rio Ferdinand and Nemanja Vidic at the heart of the defence.
After also showing his versatility by playing right-back against Blackpool on the final day, the England Under-21 international looks likely to enjoy more opportunities next term following the departure of fellow defenders John O'Shea and Wes Brown to Sunderland.
Sir Alex Ferguson has clearly been impressed with the confident Londoner and wasted little time in offering him fresh terms.
"I am delighted Chris has signed a new contract," enthused the boss to ManUtd.com. "Chris has been outstanding since joining us from Fulham last year, he is an extremely talented young defender, he’s quick, strong and reads the game well, he is a great asset to the team."
Smalling had no hesitation in extending his agreement with the Reds until the end of the 2015/2016 season and is delighted with how his Old Trafford career has taken off since moving north.
"This is a great club and, in the short time I have been here, I have already achieved more than I could have ever expected to," he told ManUtd.com. "I am looking forward to a long and successful career at Manchester United."
Smalling made 34 appearances for the champions last term, scoring once - in the Carling Cup win at Scunthorpe.
The 21-year-old is due to link up with the rest of the squad on tour in the United