Toro Rosso has completed a deal with Ferrari to use a 2015-spec Formula 1 engine next season.
Both Red Bull-owned teams were without a power supply for 2016 after requesting to end their deals with Renault at the end of the season.
Toro Rosso opened talks during the season with Ferrari over the possibility of a supply to reignite a partnership that previously ran between 2007 and 2013.
It is understood the deal was done before the Abu Dhabi Grand Prix weekend but it required a number of other things to fall into place before an announcement.
The first hurdle was cleared on Wednesday when the FIA granted permission for Ferrari to supply Toro Rosso with a 2015-spec unit.
The current regulations do not allow for two different specifications of power unit from one manufacturer to be used in a single season, with special dispensation required from the FIA.
After the season-ending Abu Dhabi Grand Prix, Toro Rosso driver Carlos Sainz Jr said he was looking forward to having "an even more Italian team" next year.
"It's looking better," he said before Toro Rosso's plans were confirmed. "We might have a bit more horsepower.
"When everyone just flies past you it's very desperate.
"It can only get better and I have full trust that Toro Rosso will do a step forward in terms of reliability, pitstops, and more grip.
"We have a good chance for next year."
On Friday morning, Red Bull announced it would continue to use Renault power next season, although the engine will be badged by TAG-Heuer.
It followed Renault's announcement it will make Lotus its works-outfit in 2016.
Ferrari and Toro Rosso released short statements confirming the agreement, adding that track testing of the new combination will begin at pre-season testing in Barcelona.