The 32-year-old Jamaica international saw his opportunities limited by knee last season admits he was raring to begin his 13th season with Wanderers.
"I want to thank everyone for the opportunity to sign on here for another year - a club where I have played for so long," Gardner told the club's website.
"I have been at Bolton almost my entire career and I wanted to stay here longer. I have been very happy here and so has my family.
"I'm looking forward to this pre-season because it is a fresh start. I hurt my knee just after the season started last year and I had to play catch-up.
"I had a bit of a break in the summer and went back to Jamaica for two weeks to give my muscles all the rest that I needed and spend time with my family.
"It was important that I prepared myself right because this is a big season for me and I want to make sure that I enjoy it."