Drivers, engineers and controllers at London United and London Transit will walk out on Friday, August 29 and Monday, September 1 in a dispute over back pay.
Unite the union says members are angry that parts of a new pay deal are not being backdated to December, leaving drivers hundreds of pounds out of pocket.
The row follows First Bus buying the companies earlier this year from RATP.
Unite also claims London United is trying to change the pay anniversary for some staff and refusing to reinstate shift work premiums.
Unite general secretary Sharon Graham said: “This is underhand and disgraceful behaviour from a company making millions from London bus passengers. To try and refuse to pay money owed since December shows an utter disregard for its workers and the hard work they do day in, day out.
“Our members won’t stand for such behaviour and Unite will back them all the way in this dispute with a company that has a history of anti-worker behaviour.”
London United and London Transit run about 90 routes from eight depots across west and south west London, including Fulwell, Hounslow, Park Royal, Shepherds Bush and Westbourne Park.
Regional officer Callum Rochford warned the strikes could make going back to school “even less popular” unless the row is resolved.
More strike dates could follow if the dispute is not settled.
Routes set to be affected include: 13, 18, 23, 31, 33, 49, 65, 70, 71, 72, 85, 94, 105, 110, 116, 117, 148, 203, 216, 218, 220, 224, 235, 272, 281, 283, 290, 293, 295, 371, 406, 411, 418, 419, 423, 440, 452, 467, 613, 662, 665, 681, 696, 698, C1, E3, H22, H37, H98, K1, K2, K3, K4, K5, KU1, KU2, KU3, N13, N18, N23, N31, N33, N65, N72, N85, N94, N105, N148, N220, N281, N295.
First Bus has been contacted for further information.
