Kendrick, 31, had been suspended for a year after a positive test following a match at the French Open. The Court of Arbitration for Sport on Monday cut that to eight months, making Kendrick eligible to return to play Jan. 21.
The International Tennis Federation had suspended Kendrick last month after he tested positive for the stimulant Methylhexaneamine. He said the substance was part of a treatment for jet lag and that he wasn't seeking a performance advantage.
Investigators agreed with that contention but said Kendrick was responsible for taking a banned substance.
In its ruling, the CAS said Kendrick relied only on information given by a blog on the Internet that claimed the jet-lag pill was approved by international anti-doping agencies and he should have checked with other authorities.
Kendrick is No. 120 in the world rankings and has been ranked as high as 69th in his career. A professional since 2000, he's never won an ATP tournament and never advanced beyond the second round of a Grand Slam event.