Mr Walker has been appointed the portfolios of science, information technology, innovation and arts.
Ms Bates resigned from cabinet on Friday for health reasons.
She had been under pressure for months over her contact with lobbyists.
Only this weekend it was revealed she appointed a friend to the board of Screen Queensland.
Ms Bates remains in the Parliament representing her Gold Coast seat of Mudgeeraba.
Mr Walker says he is looking forward to his new position.
"I want to see all aspects of our lively arts scene - from high culture to broad community participation - given the exposure and support it deserves" he said.
Mr Newman says the appointment is well deserved.
"Ian will play an important role in overseeing initiatives to drive the arts sector across the state and ensure the arts is accessible for all Queenslanders," he said.