Instead he has turned out to be one of their worst signings in recent history, costing £7 million.
The news was confirmed by manager Kenny Jackett, who told The Express and Star: "It is just a loan deal at the moment and the finances are structured around him playing – how many appearances he makes and whether they are successful. It’s a really good opportunity for him because he’s going to a Premier League club.
“It’s a really good chance for him to build on what he has done at Sheffield Wednesday."
Johnson goes straight into a relegation fight with the Hammers sitting in 19th, three points from safety.
His CV gives a warning to the Hammers however; Johnson has been relegated in three straight years - in 2010/11 with Birmingham, 2011/12 with Wolves, and in 2012/13 with Wolves again as they dropped into League One.
During his time at Birmingham he was hailed as a key figure in a reliable backline, despite their eventual relegation. This saw Wolves tempted into spending the sort of money they did on him, but the move badly backfired.
Johnson spent three months at Sheffield Wednesday on loan earlier this season, and they too are staring at relegation, sitting 20th in the Championship.
Now departed for another crack at the big time, there remains no love lost for the former Wolves skipper among fans.
For many fans the thought of Johnson back in the Premier League is simply laughable. While they haven't been fortunate to get a fee for him, it's just a loan move, they appear determined to sit back and enjoy from a safe distance.
Roger 'Relegation' Johnson off to West Ham. They'll definitely get relegated now! That would make 4 seasons in a row... #wwfc— Steve Lloyd (@lloydy273) January 6, 2014
Roger Johnson back in the Premier League? I needed a laugh. Popcorn at the ready! #wwfc— Frederika (@astersymbiont) January 6, 2014
signing Roger Johnson in an attempt to avoid relegation is like sacking Mick McCarthy to appoint Terry Connor.. #wwfc— Tom (@t0mstanley) January 6, 2014