Felipe Nasr has joined Williams as the team's official test and reserve driver and will take part in several Friday practice sessions.
The 21-year-old Brazilian, who finished fourth in last year's GP2 Championship with Carlin Motorsport, will attend this season's grands prix will Williams while also taking driving in three tests and five FP1 sessions.
"I'm really happy to be joining the Williams family," said Nasr.
"They have a great history in the sport and some of the greatest Brazilian drivers of all time have driven for the team, so it's an honour to join names such as Piquet, Senna and Massa.
"This is a fantastic opportunity for me to make the next step in my career and I can't wait to get behind the wheel of a Formula One car for the first time in Bahrain"
Team owner Frank Williams has welcomed Nasr's signing, believing the youngster will be a welcome addition to the team.
"Felipe has a strong track record of success in his career so far and we have been watching him closely for a while," he said.
"We have a track record at Williams of bringing through new talent and giving them a chance to show what they can do on the world's biggest stage.
"By driving in five FP1 sessions this season, Felipe will have the perfect chance to showcase his skills and I'm confident he will be a strong addition to our driver roster."