Appearing in the city where he won an Olympic gold medal as a member of the United States team last summer, Anthony helped the Knicks fight off a second-half comeback bid.
After trailing by 15 at halftime, the Pistons closed within four late in the third period. New York built its first-half lead with a 16-0 run in the opening quarter.
Soon after the completion of the game, it was announced in New York that Anthony had been voted onto the Eastern Conference starting lineup for next month's All-Star Game.
Amar'e Stoudemire added 17 points for the Knicks and J.R. Smith had 16 points to go with six rebounds.
New York's Iman Shumpert played for the first time this season after undergoing knee surgery during last year's playoffs. He finished with eight points.
Will Bynum came off the bench to score 22 for the Pistons.
This was the seventh NBA game, including exhibition contests, to be played in London. This was the only game scheduled for both teams during a seven-day stretch so they could recover from the trans-Atlantic trip.