The Swiss will fulfill the role for a fifth time, having first worked for the team as a test driver in 2008.
From 2009 to 2011 Buemi raced for Red Bull's sister team, Toro Rosso, competing in 55 grands prix.
The 26-year-old was not retained for a fourth season, but he returned to Red Bull in 2012 take on his current duty.
As well as F1, Buemi recently won the World Endurance Championship title with team-mate Anthony Davidson.
"I'm very pleased to take on another season as reserve driver at Infiniti Red Bull Racing," Buemi said in a statement.
"It is like being part of the family now and I have a good working and personal relationship with everyone at the team.
"I'm looking forward to helping with the development of the RB11 in any way I can. It should be an exciting season and I'm delighted that I will be a part of it."