The Oklahoma City Thunder have appointed Mark Daigneault as their head coach, the NBA franchise announced on Wednesday.

Daigneault steps up from his role as assistant to replace new Chicago Bulls coach Billy Donovan, who left the Thunder after five seasons in charge following a fourth consecutive first-round exit in the playoffs.

The 35-year-old Daigneault, who becomes the fourth head coach in team history, first joined the Thunder as head coach of NBA G League affiliate the Oklahoma City Blue in 2014 before being added to the Thunder's coaching staff in 2019-20.

"The opportunity to be the head coach of the Thunder is truly a special honour," said Daigneault, who also served as a Thunder assistant in 2015-16.

"Over my six years in Oklahoma City I've developed a deep commitment to the organisation and a care for what is truly a special community that I call home. 

"From my first day here, my values have always been aligned with those of the organisation, and I'm looking forward to helping them continue to be lived out on and off the court.

"I want to thank Mr [Clay] Bennett, Sam [Presti] and the entire organisation for the opportunity, and I'm grateful to all the coaches, staff and especially players who have helped me throughout my career."

Daigneault spent five seasons as head coach of the Blue, amassing a 143-107 record while leading the team to three consecutive division titles and four playoff appearances.

He guided the Blue to a franchise-record 34 wins during the 2018-19 G League season.

"We are thrilled to have Mark assume the role of head coach of the Oklahoma City Thunder," said Thunder executive vice-president and general manager Presti. "He has been a selfless and effective leader within our organisation since his arrival in 2014.

"Mark is a values-based leader, continuous learner, and someone that will help us continue the repositioning of our organisation on and off the court.

"The amount of head coaching experience and diverse experiences through his tenure with the Blue is rare for someone his age.

"He has also shown the ability to empower both the players and staff he works with, and we are confident that he will help us continue to modernise our approach as an organisation in a constantly evolving industry.

"Most of all, Mark has a great belief in and commitment to Oklahoma City and he will be a tremendous ambassador for our state."