As is typical of hummingbirds, male Cinnamon Hummingbirds do not participate in nest construction, incubation, or care for the nestlings.
Breeding is reported from western Mexico from November-February, in June-July, and in September (Howell and Webb 1995), and on the Yucatan Peninsula in February-April and from August-November (Howell and Webb 1995); in El Salvador in July and October (Dickey and van Rossem 1938); in Nicaragua in March and November (Martínez-Sánchez and Will 2010); and in Costa Rica from December to May or June (Stiles and Skutch 1989).
The nest is a cup placed on horizontal branches. The nest is built using plant material to stick with spider web and decorated with bits of lichen. The clutch is 2 eggs; one egg measured 14.4 x 8.8 mm (Dickey and van Rossem 1938). Little more is known about the breeding biology of Cinnamon Hummingbird.