Jean Alesi has signed for Jordan for the remaining Grand Prix of this season to replace sacked Heinz-Harald Frentzen, who is to move to Prost to take over from the Frenchman.
The pair's first drives for their new teams will be at the Hungarian Grand Prix on August 19th.
Alesi's contract with the Prost team was dissolved by mutual agreement, while Frentzen was sacked by Jordan on July 25th, just before the German Grand Prix at Hockenheim.
Alesi rejoins his former boss Eddie Jordan 12 years after winning the 1989 Formula 3000 Championship for Eddie Jordan Racing.
"I am overjoyed by this development in my career," Alesi said today.
"Eddie launched me into Formula One, so to return to race for him after all this time is something very special.
"Although I will not be able to test the car before racing in Hungary, I feel so motivated that I don't believe this will be a problem... I am very excited."
Jordan was also pleased with the signing.
"I am delighted Jean is joining us again," chief executive Eddie Jordan said.
"His experience will be invaluable for us, but equally important will be his energy and enthusiasm.
"He is a great motivator and will drive the Jordan Honda EJ11 with real fire in his belly.
"With Jean alongside Jarno (Trulli), Jordan now has a charismatic and vibrant pairing which we hope will be transferred into powerful results on the track.
"There has not been a year goes by when Jean does not come to talk to me about driving for Jordan... we are old friends so this is normal.
"But we only struck this deal once Jean was free to join Jordan.
"Alain Prost and I are also very good friends and it is important to make it clear that there is absolutely no animosity over the course of events which have led to Jean joining Jordan."
Riccardo Zonta, who raced for Jordan in Hockenheim and earlier this year in Canada, will resume testing duties for Jordan Honda in his role as the team's third driver.
Prost said he had released Alesi so as not to upset the team's balance.
"It is essential to preserve the team's harmony while we are building up Prost Grand Prix's future and consolidating our strategy for the upcoming years... this is why I chose to release Jean.
"I am delighted to welcome Heinz-Harald Frentzen to our team. His achievements in the last few years place him among the best drivers.
"He will be a strong asset for us for the remainder of the 2001 season."
Frentzen said: "I am happy Alain Prost offered me the drive for the last five grands prix. It was very difficult to turn down the opportunity to tackle this new challenge and I am looking forward to supporting the team for the rest of the season."