Razgatlioglu replaces long-time Yamaha rider Alex Lowes, whose departure from the Japanese manufacturer was confirmed on Sunday.
The Turkish rider stepped up to WSBK in 2018 with the Puccetti Kawasaki team, finishing ninth in his rookie season with podiums at Donington and San Juan Villicum.
He stayed with the outfit in 2019 and scored his maiden win in the first race at Magny-Cours last weekend, before beating Jonathan Rea to the top spot again in the superpole race.
“Toprak Razgatlioglu is the most exciting young rider in WorldSBK and I’m both happy and proud that he will race for Yamaha in 2020.
Current Yamaha rider Lowes is set to join newly-crowned five-time world champion Rea at the works Kawasaki squad next season.
Leon Haslam was expected to make the switch to the factory-backed Puccetti squad in place of Razgatlioglu, though this move now does not look assured, as the team is rumoured to be keen on securing a younger talent.
Toprak Razgatlioglu, Turkish Puccetti Racing
Photo by: Gold and Goose / LAT Images