Gallant defeated Michael Murphy, a former health minister, and Nick Duivenvoorden, a former mayor of Belledune, on Saturday.
Gallant won 59.26 per cent of the points awarded in the Liberal leadership race.
Murphy came second in the race with 37.9 per cent of the points and Duivenvoorden received 2.7 per cent of the points.
In what was a bitter leadership race at times, Gallant immediately called for party unity as the Liberals leave Moncton.
But Gallant also had a direct message for Premier David Alward.
“We will reach out to you, we want to support you when you are doing the right thing for the province, because we are in this to make the lives of all New Brunswickers better,” he said.
Gallant’s first challenge will be to get a seat in the legislative assembly.
“At the end of the day, that is an important component to the plan leading up to the next election, but it is a little premature tonight to start talking about that,” Gallant said.
Former Liberal leader Shawn Graham said on Friday that he intended to serve the remainder of his mandate in the riding of Kent. However, Graham said he would be willing to speak with the new leader.
Gallant also used his acceptance speech to make a direct criticism to the Progressive Conservatives.
The new Liberal leader said he was willing to work with the Alward government, but he was “disappointed” the party registered a dog “to ridicule our [voting] process.”
The party’s executive director registered his dog and voted online in the Liberal leadership contest.
'The torch has been passed'
When speaking to reporters on Saturday, Murphy was conciliatory in defeat.
The former health minister said he had a “very good run in this campaign” and he said he was vocal on the issues that are important to him.
“I can pinpoint that Brian ran a really good campaign. He worked it and travelled days on end, so it is not necessarily what lost it for me but what won it for him,” he said.
“It’s a little bit like what [former U.S.] President [John F.] Kennedy said, the torch has been passed to a new generation and that’s the way it is. And that’s ok.”
Seat in the legislature
Progressive Conservative MLA Bruce Fitch congratulated all three Liberal leadership contenders.
He said Gallant "seems to have that Shawn Graham feel about him."
The Tory cabinet minister also said he thought the new Liberal leader will try quickly to get a seat in the legislature.
"It is so much more effective to be on the floor of the legislature for people to get to know you," he said.
Fitch said he had hoped Murphy had pulled out a victory so they could have renewed some of their past debates.
"I was kind of looking forward to debating him in the house. I had some barbs and quips ready to go," Fitch said.