1896, originally a trade name, from towel (n.) + -ette.
Entries linking to towelette
towel n.
mid-13c., from Old French toaille (12c.), from Frankish *thwahlja, from Proto-Germanic *thwahlijan (source also of Old Saxon thwahila, Middle Dutch dwale "towel," Dutch dwaal "altar cloth," Old High German dwehila "towel," German dialectal Zwehle "napkin"); related to German zwagen, Old English þwean "to wash." Spanish toalla, Italian tovaglia are Germanic loan-words. To throw in the towel "admit defeat" (1915) is from boxing.
-ette
diminutive word-forming element, from Old French -ette (fem.), used indiscriminately in Old French with masculine form -et (see -et). As a general rule, older words borrowed from French have -et in English, while ones taken in since 17c. have -ette. In use with native words since late 19c., especially among persons who coin new product names, who tend to give it a sense of "imitation, a sort of" (for example flannelette "imitation flannel of cotton," 1876; leatherette, 1855; linenette, 1894). Also in such words as lecturette (1867), sermonette, which, OED remarks, "can scarcely be said to be in good use, though often met with in newspapers."