Finland's Valtteri Bottas will join Pastor Maldonado at Williams next season after the British team announced their 2013 driver line-up on Wednesday.
Bottas, who was been the team's test driver since 2010, steps up in place of Brazil's Bruno Senna.
Venezuela's Maldonado, who brings substantial sponsorship with him from his country's state oil company PDVSA, has been rewarded for winning this season's Spanish grand prix, the team's first race victory since 2004, with a third year at the team.
"In Pastor and Valtteri we have two of the most exciting talents in motor racing and I am especially excited about what 2013 can bring for Williams," team principal Frank Williams said in a statement.
"Pastor has always demonstrated remarkable pace and this year has seen him mature as a racing driver. Valtteri is quite simply one of the most talented young racing drivers I have come across and we expect great things from him in the future."
The 23-year-old Valtteri, a protege of McLaren's double world champion Mika Hakkinen, has been groomed by Williams over the past two years and his lap times during race weekends this season have been impressive. The Finn was also the GP3 champion in 2011.
He was even being linked to McLaren as a possible replacement for departing 2008 world champion Lewis Hamilton.
"It has always been my life-long dream to compete in the Formula One World Championship," he said.
"To do so with one of the most legendary teams in the sport is incredibly special."
Senna, the nephew of former racing great Ayrton Senna, said he was proud of being the most consistent points scorer for Williams this season.
"Since the beginning of my program with Williams I accepted that I had to share the car with Valtteri Bottas in 15 Fridays as a part of his preparation for a likely debut in 2013"," Senna said in a statement on Wednesday.
"It has been extremely satisfying to be the team's most regular point scorer and for me to demonstrate my pace in all 20 races," added the Brazilian, who finished 16th in the drivers' championship with 31 points in his first full season of racing.
"I have learned a lot and improved considerably through the season. I have had a relatively short career so far and feel as though I have come a long way in just a few years."
While he did win, Maldonado has proved accident prone, however, leading to suggestions that his financial muscle rather than his ability spared him the axe at the expense of Senna. That suggestion was dismissed by Williams' executive director Toto Wolff in a phone conference on Wednesday.
"I would rather have someone with big speed and a heavy right leg who makes mistakes rather than someone who can't get that fast, you either have it or you don't, " he said.
"Pastor has learned a lot from his mistakes which is difficult for a driver and I think we'll see a much improved driver next year."
2013 Formula 1 line-up:
Red Bull-Renault - Sebastian Vettel, Mark Webber
Ferrari - Fernando Alonso, Felipe Massa
McLaren-Mercedes - Jenson Button, Sergio Perez
Lotus-Renault - Kimi Raikkonen, Romain Grosjean*
Mercedes - Lewis Hamilton, Nico Rosberg
Sauber-Ferrari - Nico Hulkenberg, Esteban Gutierrez
Force India-Mercedes - Paul di Resta, (Open seat)
Williams-Renault - Pastor Maldonado, Valtteri Bottas
Toro Rosso-Ferrari - Daniel Ricciardo, Jean-Eric Vergne
Caterham-Renault - Charles Pic, (Open seat)
Marussia-Cosworth - Timo Glock, Max Chilton*
HRT-Cosworth - Pedro de la Rosa, (Open seat)
* - driver has yet to be officially confirmed but is expected to be named