Pharrell filed legal papers Monday in federal court in Manhattan. He's seeking a declaratory judgment of non-infringement.
The two artists have been in dispute for the past several months over the issue.
A lawyer for Will.i.am declined to comment.
Will.i.am has owned the "I AM" trademark since 2001. He filed objections in March and May against Pharrell Williams' company, i am OTHER, that launched in 2010.
Will.i.am uses "I AM" for his businesses, including his charity foundation I AM ANGEL.
Pharrell's i am OTHER produces the hit web series "Awkward Black Girl" and other web series.