Toro Rosso has agreed a three-year deal with Honda for a supply of the Japanese manufacturer's Formula 1 engines, starting next season, Autosport has learned.
Earlier this year Red Bull and Honda first began talks regarding an engine supply for Toro Rosso, which has run Renault power this season.
Honda was keen to take on a second team after its Sauber arrangement fell through, but discussions over Toro Rosso broke down during the summer.
However, McLaren's desire to end its relationship with Honda revived the deal, with McLaren requiring Toro Rosso to part with Renault to free up a supply of the French manufacturer's engines.
Following extensive talks an agreement has been reached by all parties, though official confirmation is not expected until later in the Singapore Grand Prix weekend.
Sources close to the deal have confirmed to Autosport that Toro Rosso has agreed a three-year deal from 2018 with Honda, taking it to the end of the current F1 engine regulations cycle at the end of 2020.
While preparations for next year's car are already well under way, a decision has at least come earlier than when Toro Rosso agreed a switch from Renault to Ferrari power in December 2015 for the following year.
Toro Rosso's switch to Honda power means the outfit will start its third consecutive season with a different supplier next year.
When talks with Toro Rosso began, Marko told Honda chief Masashi Yamamoto he was interested in Red Bull switching in the future if Honda improves its performance sufficiently.
With the Toro Rosso deal now done, such a tie-up with the senior team in the future remains a strong option - especially as Autosport has learned Renault is working to end its Red Bull deal at the end of 2018.