The Falkirk West MSP has swapped his role as justice minister with Humza Yousaf and will now be transport secretary.
It comes as three ministers leave the cabinet in the biggest reshuffle carried out by the current First Minister.
Going is health secretary Shona Robison, while Keith Brown is leaving his economic portfolio to concentrate on being SNP deputy leader, and Angela Constance has quit as communities secretary.
Ms Robison is replaced by Jeane Freeman, while Derek Mackay becomes cabinet secretary for finance, economy and fair work.
Shirley-Anne Somerville replaces Ms Freeman as social security secretary and Aileen Campbell is communities and local government secretary.