Marini, younger brother of former Repsol Honda world champion Valentino Rossi, joins the factory HRC team after spending three seasons in MotoGP at his brother’s VR46 Ducati squad.
The Italian, 26, was the last in a long run of rumoured candidates for the seat abandoned by Marquez, including Johann Zarco, Maverick Vinales, Aleix Espargaro, Miguel Oliveira, Fabio di Giannantonio and Pol Espargaro.
Honda’s initial insistence on offering just a single-year contract prompted most riders to step back, leaving di Giannantonio, losing his Gresini Ducati ride to Marquez, as favourite for several weeks.
But HRC’s stance softened in order to get the Marini deal over the line and the Italian has signed to helped rebuild Honda’s flagging MotoGP project on an initial two-year contract.
Although unable to match the race winning exploits of team-mate Marco Bezzecchi, Marini, who has never hidden his desire to ride for a factory team, took his first MotoGP podium and pole this year and finished eighth in the world championship.
Perhaps as importantly, Marini is considered a smart, analytical rider, famed for his precise feedback and desire to spend hours combing through the data. Qualities Honda will hope can help bring the RC213V back to the front.
Marini will join 2020 world champion Joan Mir at Repsol next season with another Ducati rider, Johann Zarco, joining LCR alongside Takaaki Nakagami.
di Giannantonio is expected to take over Marini’s VR46 place alongside Bezzecchi, on year-old GP23s next season.
Marini will make his Repsol Honda debut in tomorrow's post-race test (Tuesday).