The former governor of Massachusetts prevailed in the crucial Rust Belt battleground by the slimmest of margins, taking it by a single percentage point.
In all, his haul from the evening was six states out of the ten voting.
However, wins in Oklahoma, North Dakota and Tennessee helped to keep alive the hopes of his main conservative challenger, Rick Santorum.
Likewise, a victory for Newt Gingrich in his home state of Georgia gave the former House speaker reason to hang around in the race, especially as it takes a detour through the South in the weeks to come.
In terms of numbers alone, the night belonged to Mr Romney. His Super Tuesday triumphs saw the tally of delegates pledged to support him for the Republican presidential ticket doubled. Of the 419 at stake, he took 212, with his total now more than that of his three remaining challengers combined.
But not for the first time, Mr Romney’s victory was not convincing enough to hush talk that he fails to electrify the base, and cannot win over conservatives.
Speaking as the results began to trickle in, the leading candidate appeared to acknowledge that he has some way to go before he receives the adulation of Republican rank-and-file. “I’ve listened, and I’ve learned. I hope I am a better candidate for it,” he told supporters in Boston.
Having digested the results overnight, Mr Romney was in a more defiant mood yesterday, saying that he was “prepared to fight all the way”.
He added: “We’ve got the time and the resources and a plan to get all the delegates, and we think that will get done before the convention.”
Given the deep pockets of himself and his backers, Mr Romney is well-equipped for a long campaign. But many within the Republican elite were hoping for a knock-out blow to be delivered sooner, allowing the frontrunner to focus his attack on President Barack Obama.
“We’re in this race, and we’re in it to stay,” Mr Santorum told supporters at a Super Tuesday party. “We have won in the West, the Midwest and the South, and we’re ready to win across this country.”
Those around the former Pennsylvania senator are opening calling on Mr Gingrich to step aside, allowing conservatives to rally around their man.
Throughout the protracted process of choosing a Republican presidential candidate, the right-wing vote has been split, to the benefit of the more moderate Mr Romney.
But Mr Gingrich appears determined to resist calls for him to fall on his sword.
Moreover, a storming victory in Georgia has only served to strengthen his resolve. He pulled in 47 per cent of votes in the state that saw the start of his political career.
Gingrich campaign strategists are hoping it will be a springboard for a push through the South. The next states to vote are Alabama and Mississippi.
But Mr Santorum’s deeply conservative views on social issues chime well with the religious right in the Deep South.
Nonetheless, Mr Gingrich sounded confident in his analysis, suggesting his plodding campaign could yet prevail over his rivals’.
“There are lots of bunny rabbits to run through. I’m the tortoise, I just take one step at a time,” he said.