Gear, the discarded All Black winger, has signed a one-year contract with the southern franchise, part of a two-year deal with the New Zealand Rugby Union.
He is joining the Hurricanes exodus after eight years with the Wellington franchise.
"The past few weeks have been challenging, with lots of soul-searching and discussions with my family about what was best for me, and for them," Gear said.
"It was not an easy decision to leave the Hurricanes, but I believe I am making the best decision for me.
"I thoroughly enjoyed the team environment with the New Zealand Maori team under Jamie [Joseph] last year, and I'm looking forward to joining him and the Highlanders."
Gear's signing is a coup for the Highlanders, who have been on the lookout for some strike power.
Gear will team up with the likes of Ben Smith and Kade Poki in the backfield for the Highlanders, giving them another game-breaker, which they undoubtedly need.
Highlanders coach Jamie Joseph said the signing of Gear was a tremendous boost for the franchise.
"Despite missing out on the All Blacks for the World Cup, he is committed to wanting to get back into the All Blacks and is excited about bringing his family down here and playing for the team," Joseph said.
"He had to make sure the town fitted him and the environment suited him. It was a big decision for him to make to come down here."
Joseph said the signing showed the Highlanders could now attract top talent, which might not have been the story a couple of years ago.
"Hosea is a guy who desperately wants to get back into the All Blacks and believes this team can be one which can do that."
Gear (27) is to become a father next week to twins.
His parents also live in Wellington.
Joseph said he never pressured Gear to make a quick decision.
"It will be hard for him to leave and it was a big call for him. He had a lot of things to weigh up and consider."
Joseph had made no secret of the fact over the past couple of months he was chasing a player who could turn matches and give some firepower to his team.
The side last season had a solid forward pack but lacked a player who could turn matches in the backs.
There were suggestions of signing a player from overseas but Joseph said it was not simple, and took time.
"We're not looking just in New Zealand but offshore. [It] means you have to take a lot more things into consideration. They are playing in another country, in another competition and at another level. But if they are good enough we will look at them. It is not as easy as it sounds."
Joseph had coached Gear for Wellington and also New Zealand Maori, and had a good handle on the winger.
Gear first played for the All Blacks in 2008 and had an outstanding season last year, starring for New Zealand Maori and getting into the All Blacks northern hemisphere tour.
He was unlucky to miss out on the World Cup squad, after injury meant a late start to his international season.
