Mattiusi Iyaituk was born in a hunting camp not far from Cape Smith (now called Akulivik). He moved with his family to Ivujivik in 1955. Iyaituk attended various schools in the North and in the South. In Montreal, he received police training, and became a policeman in Ivujivik. After receiving a Canada Council grant, he resigned from the force in 1984 to devote his time to carving and hunting.
His early sculptures, dating from the 1960s, were heavily influenced by the work of his older brother, Nutaraaluk. In the late 1970s, Iyaituk developed his own "abstract" carving style, blending traditional subjects and techniques with innovative modern ones. He is noted for reviving the old community style of using ivory, bone, and antler inlay with dark soapstone, and drilling small dots to represent parka trim.