Former Leeds midfielder Howson burst from the halfway line, shrugging off poor challenges from Yaya Toure and Micah Richards before slotting the ball beyond the dive of Joe Hart.
The goal summed up the home side's performance; they looked lacklustre throughout, missing the reassuring presence of Vincent Kompany with Joleon Lescott and Richards in particular having a torrid time at the heart of the Blues' defence.
The hosts did manage to claw their way back into the game twice through a Jack Rodwell double - his first Premier League goals for the club - but they were second best for long periods to an impressive Norwich side who ended their campaign on a high.
The visitors took the lead on 26 minutes when Anthony Pilkington finished sweetly with his right foot after some flimsy defending by the home side allowed Wes Hoolahan to prod the ball into his path.
The lead lasted just three minutes before Rodwell levelled. Samir Nasri played the ball into Edin Dzeko's feet and his lay off was perfect for the former Everton man who hammered the ball beyond John Ruddy.
Norwich could easily have gone into the break ahead but they were denied a penalty when Pablo Zabaleta ploughed into the back of Pilkington, referee Mark Halsey - making his final Premier League appearance - awarding a corner instead. As the ball came back in the ball appeared to clip Richards' arm but again appeals for a spot-kick were waved away.
Norwich reclaimed their lead on 54 minutes when the influential Robert Snodgrass found space on the right and delivered a pinpoint low cross for an unmarked Grant Holt to tap in at the far post.
Again the home side were quick to reply as Rodwell raced onto a long ball from Toure and outpaced Steven Whittaker to fire into the far bottom corner.
But City's deficiencies were at the back throughout and Howson slalomed through some ineffective challenges to finish clinically midway through the second half to end a miserable week for the former champions.