Former All Blacks hooker Gatland was officially appointed to the job on Wednesday in Edinburgh for next year's Lions tour of New Zealand, though the decision had already been well signposted.
"It was the best kept secret wasn't it," Hansen told reporters in Hamilton ahead of his side's Rugby Championship clash against Argentina on Saturday. "He was the obvious candidate, I said that months ago.
"He has been on Lions tours before, he understands what's required, you're bringing a group of different team members together, a little bit like a franchise, but on a bigger scale, different cultures, and that takes some work."
While Gatland may have been the odds-on favourite to lead his second Lions tour, the choice of assistants has been the subject of intense scrutiny in Britain since Eddie Jones was named as England coach.
Jones led England to the grand slam in the Six Nations earlier this year then guided his side a 3-0 victory over World Cup finalists Australia in June, though he has ruled himself out of contention several times.
Gatland's fellow New Zealander Vern Cotter will leave the Scotland role after next year's Six Nations, while Ireland's Joe Schmidt, another New Zealander, has also been tipped as joining the Lions staff.
"It'll be interesting to see who he brings with him, from a coaching point of view," Hansen said.
"That's the next thing we'll look for, with a bit of interest. And then it's about us preparing for what they're likely to bring."
Gatland, whose Wales side were beaten 3-0 by the All Blacks in a series in June, told British media after his appointment that he felt being able to pick from the four Home Nations would give him the pace and flair needed to beat the world champions.
"I'm really excited about the potential talent that's available," Gatland told Wales Online.
"We've got a team that is going to have some pace, footwork, physicality, size and experience so I'm really excited about the prospect of putting a squad together that's going to be hugely competitive."
Hansen said he felt Gatland had downplayed the challenge his side had received from Wales, but agreed the combined side would be tough to beat.
"There's no doubt he's going to be able to pick a really good side," Hansen said.
"England are playing well, Scotland have played well, Ireland are playing well, and Wales are a good side.
"So he's going to have at his disposal some quality people. It should be a good series."
(Reporting by Greg Stutchbury in Napier; Editing by Sudipto Ganguly)
