On Monday, Autosport broke the news that Ducati had made a U-turn on its decision to promote championship leader Jorge Martin from Pramac to its factory squad.
The way was paved for Marquez to go to the factory Ducati team when Aprilia announced it had signed a multi-year deal with Martin.
With Marquez stating at the Italian Grand Prix that racing on a factory bike at Pramac was "not an option" for him, Ducati's hopes of being able to keep both Martin and Marquez were dashed.
Marquez's form on the 2023-spec Ducati at Gresini this season, coupled with his high marketing value, meant the Italian manufacturer could not afford to lose him to a rival marque.
Ducati informed Martin on Sunday at the Italian GP of its decision.
On Wednesday, Ducati officially announced that it had signed Marquez for 2025 on a two-year deal to partner reigning double world champion Francesco Bagnaia.
"I am very happy to be able to wear the red colours of the factory Ducati team in MotoGP next season," Marquez said.
"Basically, from the first contact with the Desmosedici GP, I enjoyed riding it and adapted well straight away.
"From that moment on, I knew that my goal was to continue this path, to continue to grow, and to move to the team where Francesco Bagnaia has been the world champion for two years in a row.
"I am happy to be able to take this big step in 2025 and grateful for the trust Ducati has placed in me.
"Finally, I want to thank Nadia [Padovani], Carlo [Merlini], Michele [Masini], and the entire Gresini Racing family for opening the door of their team to me at a delicate time in my career.
"Now, we will continue to have fun and give it our all in what remains of the current season, which is my priority right now."
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Marquez replaces Enea Bastianini at the factory Ducati squad, who is set to ride a KTM next year - as reported by Autosport.
The move is a clear example of Marquez's authority in the championship, as in just four days he has been able to change the minds of Ducati's top management.
The Italian executives succumbed to the Spanish rider's demands following his refusal to ride for Pramac.
In the face of that bluntness and the threat of signing for KTM or Aprilia, Ducati's management was fearful of losing Marquez, the series' main attraction amid a popularity growth, in part due to the #93 rider's performances on a Desmosedici.
Although the details of the deal between the two parties were agreed at Mugello last weekend, the announcement has been delayed due to various legal hurdles.
After an eleven-year stint at Honda, with whom he won six titles out of a possible seven between 2013 and 2019, Marquez decided to end his spell at the Japanese brand and give up on the last year of his remaining contract (2024), driven by the ordeal he went through since his accident at Jerez in 2020, in which he broke his arm.
Then came four operations and a lot of confusion due to the lack of competitiveness of a very difficult bike, which led him to suffer countless crashes.
A third of the season has been enough for Marquez to use his speed, influence and image multiplier effect to persuade Claudio Domenicali and Gigi Dall'Igna, Ducati's CEO and general manager respectively, who make the most important decisions.
Dall'Igna said of the announcement: "First of all, I want to thank both Enea Bastianini and Jorge Martin for all their work with us over the last few years, and I wish them all the best for the future.
"This season, they have shown they have reached an incredible level, and we are sure they will be in the title fight until the end.
"Deciding on Bagnaia's new team-mate in the Ducati Lenovo Team was not easy, as we had a list of very strong riders to choose from.
"In the end, our choice fell on an unquestionable talent like Marc Marquez. In just a few races, he has managed to adapt perfectly to our Desmosedici GP, and his innate ambition pushes him to grow continuously.
"In the box, we will have two riders who together hold 11 world titles, and being able to count on their experience and maturity will be invaluable for our growth as well."
