Manchester United's £24 million ($39 million) pre-season signing scored inside the opening minute, his 12th goal in all competitions this season, to continue an impressive start to his career with the club.
Having fallen behind 13 times already this season, United were acutely conscious of the importance of taking the lead for a change and van Persie responded with the fastest goal of the Premier League campaign in a mere 32 seconds.
Michael Carrick threaded an accurate pass through a crowded midfield to van Persie who, back to goal, took out his marker Winston Reid with a devastating flick.
The Dutch international then enjoyed a large slice of fortune as his first-time shot deflected off James Collins and looping over luckless goalkeeper Jussi Jaaskelainen.
If the shot was fortunate, van Persie had earned it with that sublime piece of build-up skill but if United thought the outcome was secured by that early lead, they were in for a rude awakening.
West Ham responded with Kevin Nolan audaciously back-heeling a Matt Taylor free-kick into Anders Lindegaard's side-netting while a dangerous cross from Matt Jarvis forced the United goalkeeper into a desperate clearing punch.
Collins almost made amends for his role in the United goal when he came within a whisker of diverting a long shot by Taylor past Lindegaard, who dived to smother the attempt.
Andy Carroll would also squander a promising opportunity to equalise, volleying well wide from just seven yards out after United's defence had done a poor job of dealing with a routine long ball into their area.
Mohamed Diame won a corner in the opening minute of the second half before the game settled into a period of United control, started by van Persie guiding a Rooney header into the path of Tom Cleverley whose crisp, first-time shot sailed just over from 16 yards.
Rooney, van Persie, at a 20-yard free-kick, and Carrick all sent rather hopeful long-distance shots towards the Hammers' goal as the pressure mounted.
Just before the hour, Rooney, becoming increasingly influential in his by-now customary, deeper role, unleashed a superb strike from the edge of the area which Jaaskelainen turned around his post and, from the resulting corner, only desperate, bodies on the line, defending from the Hammers managed to clear a near-post scramble.
A Rafael cross was met by Hernandez with a reflex flick of the boot that sent the ball inches wide and Ferguson brought on Ashley Young in the hope of adding attacking threat.
The tactic had the desired effect, Young offering far more in the final third than the man he replaced, Cleverley. But still, this was not a vintage display of finishing from United.
Rooney placed a 69th minute shot well over while Anderson fared better from 18 yards but saw Jaaskelainen deal impressively with a viciously swerving shot.
There was the occasional warning for United -- the ball just would not come down for Taylor as he attempted to line up a shot in a dangerous position after 70 minutes -- but the traffic continued in one direction only.
And it required a fine block by Gary Demel to deny what surely would have been a second goal for van Persie after 75 minutes.
It was United's night though and the point was underlined after 82 minutes.
Hammers substitute Carlton Cole shot on the turn from six yards but Lindegaard made a superb stop before enjoying the sight of Modibo Maiga being flagged for offside as he waited to pounce on the loose ball.