The 31-year-old former England international’s contract at the Hawthorns expires at the end of this season.
Gibbs joined West Brom from Arsenal in the summer of 2017 and was instrumental in their qualification from the Championship to the Premier League last season.
Gibbs has made 10 appearances in the top flight this term for the struggling Baggies, who are 19th on the table, but he will join David Beckham’s MLS franchise come the end of the campaign.
West Brom said in a statement: "Albion left-back Kieran Gibbs will join MLS side Inter Miami when his Hawthorns contract expires this summer.
"The 31-year-old will remain with the Baggies for the duration of the 2020/21 Premier League season."
'I'm extremely excited to be starting the next chapter of my career with Inter Miami this summer,' Gibbs said on Inter Miami's official website.
'I look forward to embracing a new culture and a new challenge in South Florida.
'I'm really impressed by the vision of the club, and can't wait to play in front of The Siege, Southern Legion, and Vice City 1896.
'In the meantime, my focus and commitment remains with West Brom. I will continue to give 100 per cent for the club, as I have done since I signed, until the end of the season.'
Gibbs has been capped 10 times by the England national team.
