Baker Mayfield is holding firm to his promise to kneel for the national anthem ... saying he's proud to use his platform to speak out for human rights.

Remember, the Cleveland Browns QB clapped back at a fan who begged him to NOT take a knee this upcoming season ... saying, "pull your head out. I absolutely am."

During a virtual media session Friday, Bake was asked if he regretted going public with his kneeling plans because of social media backlash he received afterward.