Dioon tomasellii is a species of cycad in the family Zamiaceae.

It is endemic to Mexico, where it occurs in the states of Durango, Guerrero, Jalisco, Michoacán, and Nayarit.

[1] This plant grows in oak and pine-oak forest and woodland habitat.

Threats to the species include destruction of the habitat for agriculture and overcollection for horticultural purposes.

[2] It was revised in 1997, with one variety being elevated to species status as Dioon sonorense.