With 98 percent reporting, Christie took 60 percent support to Buono's 38 percent.
The runaway victory gives Christie a significant boost as he lays the groundwork for a possible White House campaign in 2016.
The governor's win was so assured that The Associated Press called the race in his favor within minutes of the polls closing.
Three polls out this week had showed Christie up by 20 or more points.
Though Christie’s campaign was looking for a big margin, it said prior to election night that anything over 50 percent would be impressive. No statewide Republican candidate has achieved that since George W. Bush in 1988.
Christie’s margin is a key piece of the puzzle for the governor as he looks ahead to 2016.
He pledged on Tuesday night during his victory speech to "finish the job" in New Jersey — but has previously dodged questions about whether he'll complete a second term as governor, a nod to the fact he's considering a presidential bid.
If he runs, Christie is expected to make the case that he'd be the most electable Republican in a crowded GOP primary, an argument his advisers believe will resonate with a party sick of losing key demographic groups like women and minorities.
To build that argument, Christie made a concerted effort throughout the gubernatorial campaign to reach out to just those voting blocs. Exit polling showed him winning women, splitting Hispanics with Buono and improving his standing among black voters by 11 percent from 2009, a considerable feat for a Republican.
His strong support among New Jersey Republicans, and his backing among independents and some Democrats following Hurricane Sandy, helped dissuade better-known Democratic challengers from entering the race.
Though Buono received some help from national Democrats and a few outside groups — like EMILY's List, which backs pro-abortion-rights female candidates — her campaign drew neither the attention nor the Democratic starpower of Virginia’s gubernatorial contest.
Christie had drawn criticism during the campaign for his decision to schedule a special election to fill the late Sen. Frank Lautenberg's (D-N.J.) seat on an odd Wednesday in October. Democrats said it was a costly choice was made to avoid boosting Democratic turnout in a way that could've hurt his own reelection bid.
Democrats also accused him of running with an eye on the presidency rather than his own state.
But neither of those attacks gained much traction, and other, more substantive Democratic critiques — arguments that Christie, who is personally opposed to gay marriage and abortion, is too extreme for the blue state, and questions about his handling of New Jersey's economy — barely got an airing during the campaign.
His next challenge is to orchestrate unexpected Republican victories similar to his own in 2014 as he heads up the Republican Governor's Association.
Christie may also have to tack to the right during his next term as governor, as much as possible in the Democratic Garden State, to win back some conservatives he may have alienated as he worked to draw Democratic support for his own reelection bid.
—This piece was updated at 12:40 p.m.