Bell, who will act as technical consultant to the team, is the most high-profile arrival. A former Renault F1 team principal, his career has also featured spells at McLaren, Benetton and Jordan, and includes winning two Formula One constructors' titles. He left Mercedes at the end of last year.
Marussia have also appointed Luca Furbatto as their new head of design. Furbatto, who will serve under technical director John McQuilliam, previously held the role of head of design at Toro Rosso, and before that spent close to a decade with McLaren. Gianluca Pisanelli, meanwhile, joins in the role of chief engineer, having served most recently as head of engineering operations at Caterham.
“We're delighted to welcome Bob, Luca, and Gianluca," said Marussia team principal John Booth, who believes the appointments will help Marussia progress to the next level.
"As ever in Formula One, we rely on the experience, tenacity and drive of our colleagues, so we're delighted to welcome our new teammates. Each of them brings a huge amount of experience from within the sport, adding further dimensions to our existing technical and engineering capability.
"It's been a dramatic but rewarding start to our 2015 season, and we're only now able to settle into more of a rhythm, allowing us to look to the future. Our focus this season is to re-build the foundations of the team and develop our internal capabilities. Whilst we seek to optimise our performance during the remainder of the 2015 season, we can also turn our attention to the next exciting chapter in our story - 2016 and beyond."
Marussia lie tenth in the 2015 constructors' standings, with their best results so far this season two 15th places, in Malaysia and China.