The 32-year-old Frenchman has been without a club since his QPR contract was brought to a premature end in April and has penned a short-term deal at the Keepmoat Stadium.
He featured for an hour at left back in a specially organised practice match against a Chesterfield XI today.
Rovers have enjoyed a great upturn in fortunes since Saunders took over last week and have picked up four points from the first two games under his stewardship.
This comes after a 19 game winless streak under former manager Sean O’Driscoll which eventually cost the former Bournemouth manager his job.
However Donny still find themselves at the foot of the Championship table and Chimbonda and his team-mates face a tricky trip to free-scoring Peterborough on Saturday.