Former unified junior middleweight titleholder Canelo Alvarez, Mexico's most popular active fighter and one of boxing's biggest stars, signed a multiyear, multifight contract extension with Golden Boy Promotions on Friday, the company announced.

The signing comes two months before Alvarez (45-1-1, 32 KOs) will challenge Miguel Cotto (40-4, 33 KOs) for the middleweight world championship on Nov. 21 (HBO PPV) at Mandalay Bay in Las Vegas in the year's biggest fight besides the record-breaking May 2 fight between Floyd Mayweather and Manny Pacquiao.

"I am loyal. It's part of my character and that's why I am extending my contract with Golden Boy Promotions," Alvarez said. "Golden Boy Promotions knows how to build a fighter and elevate him to a world stage as they have done with me and continue to do with many others. I look forward to working with Golden Boy throughout my career."

Financial terms of the deal were not announced, nor were the number of years or fights, but it is a huge signing for Golden Boy, especially in the wake of it cutting ties in January with manager Al Haymon and his deep stable of fighters, most of whom Golden Boy was promoting.

Alvarez, 25, has been with Golden Boy since 2010 and won his first world title at junior middleweight under its guidance in 2011. He outpointed Austin Trout to unify belts in 2013 in front of some 40,000 at the Alamodome in San Antonio. He followed that bout with his first loss, a decision to Mayweather in a title unification bout later in 2013 in a fight that set the all-time revenue record, which was broken by Mayweather-Pacquiao.

"Canelo Alvarez is no longer the future of the boxing -- he is the present, and with a win on Nov. 21 against Miguel Cotto, he will solidify his status as the best in the business," Golden Boy Promotions CEO Oscar De La Hoya said. "It has been a privilege to promote him during his meteoric rise, and we now look forward to many more highlights in a career already filled with many of them."