Boston Celtics head coach Brad Stevens has signed a contract extension with the NBA franchise, it was announced on Wednesday.

Terms of the deal were not disclosed by the Celtics, who hired former Butler University coach Stevens in July 2013.

Stevens has a 318-245 win-loss record since taking charge of the Celtics, with the 43-year-old's wins the fourth-most by any Boston coach in franchise history.

The Celtics will make their sixth successive playoff appearance in 2019-20, while Stevens guided the storied team to back-to-back Eastern Conference Finals between 2017 and 2018.

"Brad is an accomplished coach and an outstanding person," said Celtics lead owner and governor Wyc Grousbeck. "We are proud to have him lead our team forward in our quest for Banner 18."

"We are thrilled that Brad Stevens will continue to be our coach," said Celtics co-owner Steve Pagliuca. "He has become one of the best coaches in the NBA, and is a real leader on and off the court. This is a great day for the Boston Celtics."

The Celtics (48-23) are third in the Eastern Conference this season, behind the high-flying Milwaukee Bucks and defending champions the Toronto Raptors.

Celtics president of basketball operations Danny Ainge added: "Brad is one of the most intelligent and hard-working coaches in the game today.

"More importantly, his character and integrity have contributed to a culture that we all highly value here. Brad is a great team-mate, and a leader people want to follow. We are honoured to have him with us as we continue to pursue our next championship."