Christie, chair of the Republican Governors Association, arrived at a lunchtime fundraiser at a Bethesda restaurant to benefit Hogan and said the race's changing dynamics brought him to Maryland.
"This race is closing, and that's why I'm here," Christie said. "In the beginning, it didn't look like a race that was going to be tight, but it is tight now. That's why I'm here, and that's why the RGA is going to be here to help him because we think he's got a good chance here."
Proceeds from the event, which was closed to the news media, will go to the Maryland Republican Party's Hogan Victory Fund.
The visit by Christie signals national party interest in Hogan's underdog race in the Nov. 4 election in heavily Democratic Maryland. The New Jersey governor said he counted himself as a candidate who prevailed against the odds.
"You're talking to a guy from New Jersey, who won twice, with 750,000 more [registered] Democrats in the same kind of atmosphere," Christie told reporters as he walked from his car to the Redwood restaurant. "I feel pretty good about it. These races can be won. I'm proof of it, and that's why I'm here."
As Maryland Republican Party Chairwoman Diana Waterman greeted Christie, she gave a him a hug and said, "Governor Christie, welcome to our state. Finally."
Waterman said the party had tried for more than year to find the right time for Christie to visit Maryland.
Hogan said the event raised more than $400,000 from the 62 people who attended.
"It's a huge boost to our campaign," Hogan said. "This is a national race."
The New Jersey governor remains popular in GOP circles despite a series of investigations at home sparked by last year's closing of George Washington Bridge lanes for what appears to have been political reasons.
Christie has denied any personal involvement in the affair, which led to the dismissal of some of his top appointees.
Joe Cluster, executive director of the Maryland GOP, said he sees no downside to having Christie here. He said the New Jersey governor is still a strong draw.
"We've done very well with this event," Cluster said.
Hogan opted to use the state's public financing system, which guaranteed him $2.6 million in public funds but also limits his spending to that sum. The state and local chapters of the Republican Party, however, can continue to raise up to $3.7 million to spend on Hogan's behalf.
The Maryland Democratic Party used the Christie visit to do some fundraising of its own. It sent out an email urging supporters to donate money to fight what it called the two Republicans' "anti-choice, pro-gun agenda."
A spokesman for Hogan's Democratic rival, Lt. Gov. Anthony G. Brown, released a statement asserting that Christie is supporting Hogan because they share a conservative Republican agenda that would harm Maryland families.
"Both Christie and Hogan take extreme positions against common sense gun regulations, banning high capacity magazine clips, strengthening background checks, and protecting a woman's right to choose," Brown campaign manager Justin Schall said.
Hogan will get another fundraising boost Thursday night when former Gov. Robert L. Ehrlich Jr. is scheduled to appear at an evening event at Parker's restaurant in White Marsh. It will be Ehrlich's first appearance on behalf of his onetime appointments secretary since Hogan won the Republican nomination in June.