The non-binary star - who uses the pronouns they/them - is upset that the BRITS have decided against introducing a gender-neutral alternative to the awards.
In a statement on Instagram, Sam said: "Music for me has always been about unification not division.
"I look forward to a time where awards shows can be reflective of the society we live in.
"Let’s celebrate everybody, regardless of gender, race, age, ability, sexuality and class.”
A spokesperson for the awards said: "Sam is an extraordinary British artist and we agree with what they have said today. The BRITS are committed to evolving the show and the gendered categories are very much under review.
But any changes made to be more inclusive need to be just that - if a change unintentionally leads to less inclusion then it risks being counterproductive to diversity and equality. We need to consult more widely before changes are made to make sure we get it right."
The Academy also told its voters: "Looking to the future we still have a lot of work to do in the coming years to evolve the BRITS. The process of change isn’t something that can be fixed in just one campaign and we are committed to working together with the industry to evolve the show to be as inclusive and relevant as possible."
The awards are set to take place on May 11 at London’s O2 Arena.