Drivers employed by First Hampshire and Dorset have rejected the company's latest pay offer and will go on strike for 24 hours on Monday 10th February.
Around 60 drivers, who are members of Unite, rejected the offer as "there were too many strings attached, which would have meant a reduction to their terms and conditions".
Monday's strike will start at 4:30 and run for 24 hours.
Passengers in the Bridport, Portland and Weymouth area will be affected.
Unite regional officer Bob Lanning said, "The crux of this dispute is that our members are lagging behind the pay of their counterparts working for other regional bus operators, at a time when household bills are going through the roof."