The former Liberty Professionals man found the back of the net and set up another to help LAFC claim all three points in the home fixture at Banc of California Stadium.
The goal, his third in three consecutive league games, has taken his season tally to five, in addition to five assists.
Norway striker Adama Diomande broke the deadlock in Sunday's game in the 28th minute, having been set up by Mark-Anthony Kaye.
Blessing then made it 2-0 four minutes later after beating his marker at the far post to tap Aaron Kovar's cross into net the from close range.
Sacha Kljestan, however, pulled one back for City 14 minutes after the interval before LAFC restored their two-goal cushion through Diomande in the 82nd minute.
Two minutes later, Blessing turned provider this time as he picked up a loose ball just outside the box, made his way into the area before unselfishly picking out Diego Rossi, who shot into a virtually empty net.
LAFC sit second on the Western Conference table, while City hold the ninth spot on the Eastern Conference log.
Blessing joined Bob Bradley's side in December last year from Sporting Kansas City.
He netted three times in 26 MLS appearances involving 17 starts for the Wizards last season - in his first campaign in the topflight.