Henson had been rekindling his career at London Welsh but he decided to move on following their relegation from the top tier.
And the 31-year-old, who has amassed 33 caps and two RBS 6 Nations Grand Slams, is relishing life at the Rec.
“I am thrilled to be joining Bath this summer, and I look forward to becoming part of what looks a very exciting squad,” said Henson.
“I still very much want to be playing at the highest level, and Bath is a big club with big plans. I know what is expected of me and I can’t wait to get started.”
Henson played 11 matches for London Welsh, but injuries hampered his time at the relegated club.
But Bath head coach Gary Gold is in little doubt that Henson can have a major impact at the Rec
“We know Gavin’s qualities and have seen him work extremely hard for his team and perform at a consistently high level last season,” said Gold.
“He is still a very ambitious man and the prospect of him playing at the Rec is an exciting one. We look forward to his arrival here in Bath.”
Bath is just the latest club for Henson, who has also enjoyed stints at Toulon, Saracens and Cardiff Blues since leaving the Ospreys in 2009.
