Sam Allardyce began his spell as Irons boss with a visit from ex-Hammer Malky Mackay's Cardiff on the opening day of the season, when Kenny Miller's stoppage-time strike got his tenure off to a miserable start.
But redemption was well and truly fulfilled at the Boleyn Ground as skipper Kevin Nolan's header from a Matthew Taylor corner was followed by cracking strikes from Ricardo Vaz Te and substitute Nicky Maynard to put an insipid Bluebirds side to the sword.
West Ham will now make the trip across the capital for the Championship play-off final at Wembley on Saturday May 19th, where they will face one of the sides who were also relegated from the top flight in 2010/11 - Blackpool and Birmingham - with an instant return to the Premier League at stake.
Knowing it was do or die after losing 2-0 at home in the first leg, Cardiff went on the attack soon after the opening whistle with Miller and Mark Hudson unable to fashion serious chances.
Miller looked for a penalty call after going down in the box on nine minutes, but referee Mike Dean ruled that Winston Reid had defended legally against the striker.
And six minutes later, in a scene reminiscent of Jack Collison’s opener at the Cardiff City Stadium, the Irons snatched the lead on the day against the run of play.
The first corner of the contest was whipped in with supreme accuracy by Matthew Taylor on 15 minutes, and after Carlton Cole could only help it along, Nolan nodded the loose ball over the line from two yards.
The 3-0 aggregate scoreline almost became four moments later when Collison’s floated cross in from the right was volleyed towards goal by an off-balance Gary O’Neil, the ball looping over goalkeeper David Marshall and down onto the crossbar.
The keeper was at full stretch to keep out the midfielder’s screamer from a Vaz Te cut-back on 34 minutes, but with five left before the break the hosts would find the extra additional daylight they sought as Guy Demel slipped the ball through to Vaz Te on the right flank and the Portuguese forward shook off Andrew Taylor to cut into the box and unleash an unstoppable drive into the far corner.
The one low point for an otherwise-jubilant crowd in East London came three minutes into the second half as a crunching-but-fair challenge from Taylor left Collison in a heap on the grass.
The Welsh international - a product of the club's youth system - scored both goals in Thursday’s first leg, but was replaced by Henri Lansbury and taken to the local hospital as a precautionary measure.
The hosts spent the majority of the second period from there soaking up Cardiff pressure, happy to keep what they had, but came close to scoring again with 11 minutes to spare only for Marshall to block well from Taylor.
Maynard was West Ham’s final switch on 86 in place of Cole, and three minutes later he provided the icing on the cake for the Londoners.
After being put through on goal by fellow replacement Lansbury, the January deadline-day recruit from Bristol City produced a wonderful finish into the top corner for his first goal on the Boleyn turf.
The play-off final will now see the Hammers march out onto the Wembley turf 47 years to the exact day that Alan Sealey's brace sealed a 2-0 win in the European Cup Winners' Cup final against 1860 Munich at the old national stadium, their only major honours on the continent. The West Ham faithful will hope for a lucky omen in their hopes of a speedy return to the top division at the first attempt.