Tom Kenny -- the voice behind "SpongeBob SquarePants" -- is hitting the iconic yellow sponge with a new diagnosis ... autism.

The veteran performer, who's played SB for years, made an appearance at a Comic Con event in Detroit ... where he took questions from dedicated fans about the beloved Nickelodeon character ... and doubled down on a theory that SpongeBob is neurodivergent.

As Tom told the crowd at the convention ... SpongeBob is "kind of on the spectrum," going as far as to call the cartoon character autistic.

TK says he came to this revelation after speaking with a fan on the spectrum, who asked if SpongeBob could possibly be autistic as well. He recalled telling the fan ... autism was SpongeBob's superpower, the same way it was for that kid.

This isn't the first time that Tom has addressed SpongeBob and the possibility of him being autistic. Back in 2012, he spoke with Marc Maron and speculated then Sponge might be autistic ... citing his obsession with his job and his hyper-fixation tendencies as proof.

SpongeBob isn't the first children's character to be diagnosed with Autism Spectrum Disorder. "Sesame Street" added a Muppet named Julia to their roster ... who explicitly had autism.