The 27-year-old will join the Spanish team on a two-year deal from the start of next season, having spent two years at Team Sky.
"It's great news for us," said Movistar general manager Eusebio Unzué. "Being still a young rider and with everything that he's shown, he should be the rider who leads Spanish cycling for the next few years."
He also won the mountains classification at the Giro d'Italia after his GC hopes were scuppered by a crash with a motorbike, and most recently won two stages and the overall at the Vuelta a Burgos.
After speaking of his frustration at having to sacrifice his own chances for Chris Froome, Landa will now join a Movistar team where Nairo Quintana has a contract until the end of 2019, raising questions about who will lead the team at the 2018 Tour de France.
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