What is the adjective of cheeky?

The adjective of "cheeky" is cheeky itself. It's already an adjective.

For example:

* "She gave him a cheeky smile."

* "He had a cheeky grin on his face."

You can also use the word cheekily as an adverb.

For example:

* "She smiled cheekily."

* "He winked cheekily."