Karl Martin Sinijärv (born 4 June 1971) is an Estonian journalist and poet.

His poetry has been characterized as etnofuturist, bringing estrangement of language to the brink of self-parody.

Sinijärv's first book of poems was published in 1989 in a collection with three other poetry books by Tõnu Trubetsky, Ringo Ringvee and Märt Väljataga.

and "Jüri Üdi klubi" in Estonian public television channel Eesti Televisioon for more than 10 years.

His grandfather was futurist and socialist poet Erni Hiir.