She was initially banned for two years after testing positive for the banned medication meldonium during January’s Australian Open.
But following an appeal, the ban – imposed by the International Tennis Federation (ITF) – has been reduced to 15 months.
It means the five-time Grand Slam champion will now be free to compete at the Fren0ch Open in Paris next year.
The Lausanne-based CAS said Sharapova “bore some degree of fault” for the positive test but a 15-month “sanction” would be more “appropriate”.
The former world number one admitted taking meldonium for 10 years but said it was to help treat illnesses, a heart issue and a magnesium deficiency.
She also claimed it had entirely escaped her attention the product had been added to the banned substance list published by the World Anti-Doping Agency (WADA) on 1 January, just before the Australian Open.
An independent ITF panel found Sharapova did not intend to cheat but that she bore “sole responsibility” and “very significant fault” for the positive test.
The panel also said the case “inevitably led to the conclusion” that she took the substance “for the purpose of enhancing her performance”.
In a statement issued by her agents, Sharapova described the reduction of her doping ban as “one of my happiest days”.
“I’ve gone from one of the toughest days of my career last March when I learned about my suspension to now, one of my happiest days, as I found out I can return to tennis in April (2017),” she said.
“In so many ways, I feel like something I love was taken away from me and it will feel really good to have it back.
“Tennis is my passion and I have missed it. I am counting the days until I can return to the court.”
Sharapova said she had learned from the doping episode and hoped the ITF, tennis’ governing body, had too.
“I have taken responsibility from the very beginning for not knowing that the over-the-counter supplement I had been taking for the last 10 years was no longer allowed,” she added.
“But I also learned how much better other federations were at notifying their athletes of the rule change, especially in eastern Europe where Mildronate (its trade name) is commonly taken by millions of people.”
As a result of the ban Sharapova missed this year’s French Open, Wimbledon and the US Open, as well as the Olympics in Rio de Janeiro.