The undefeated Englishman won soundly via a unanimous 12-round decision with scores of 120-107, 120-107 and 119-109.
His opponent Johnson hasn’t been knocked out since 1997, and it was clear why at the ExCel Arena as the 43-year-old kept his guard high and made it difficult for Groves to land a clean hit.
But what Johnson brought to the ring in defence he lacked in attack and showed little variety, instead relying almost entirely on his trademark chopping right.
This didn't hold up against Grove's calm audaciousness, who as predicted proved to be a mountain too high for the Jamaican who retired in July but was tempted back to the ring by one last championship fight.
The result puts the 24-year-old Groves's undefeated run to 16 and sets him up for world title fights in 2013.
"I'm very happy with it and I've learnt a lot from that fight," said Groves.
"On more than one occasion I thought he was out on his feet and he wasn't. I fully understand why he's only been stopped once in 71 fights now."
Of Johnson's 71 professional fights to date he has won 51, drawn two and lost 18, yet he has only been knocked out once - against Bernard Hopkins in 1997.
Groves was showed quickness and energy from the first round to take it for himself before continuing to batter his opponent for the next 11, the only threat coming via Johnson's right shots that found their target much less frequently.
Johnson's uncanny ability to take punch after punch was what saw him through trouble spots against the ropes in the sixth and seventh stanzas, and was possibly also saved by the bell in the sixth.
The eighth and ninth saw him penetrate Groves's steel fortress for the first time and he threw some strong hits that fell just short or rattling his less-experienced counterpart.
Groves sent Johnson down in the final round, but it was not enough for the knockout he sought and his win was validated only by the judges' scores.
On the undercard, Billy Joe Saunders took a unanimous points win (117-112, 116-113, 115-114) over Nick Blackwell to clinch the British middleweight title while the popular Frank Buglioni scored his fifth knockout with a second-round stoppage of Ciaran Healy which moves the 23-year-old super-middleweight to 7-0.