Niemi has also written Svålhålet (really roughly translated into English as The hole of tough fat), Kyrkdjävulen (The church devil), "Mannen som dog som en lax"(The man who died like a salmon) and Blodsugarna (the bloodsuckers).

He first became famous by writing poetry, and he has published many collections of poetry, such as Änglar med mausergevär (Angels with mauserguns) , Med rötter här uppe (With roots up here) and his very first, Näsblod under högmässan (Nosebleed during the high mass). He has also written many works for the theater.

All of his books contain some Meänkieli language, because Pajala, and the rest of Tornedalen, is partly inhabited by people of Finnish origin, although the area has been Swedish territory since the establishment of national borders in the area.

Niemi was educated in Luleå but currently resides in Pajala.