There are 91 9-letter words that end with 'o'.
Note: These 91 9-letter words that end with 'o' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words end with to, do, ro, no, go, lo, oo, io, co, mo, so, ho, bo, zo, ko, po, vo, eo, ao, yo, jo, fo, uo, wo, xo.
2-letter words end with 'o' (12)