The story
Coined by American artist, art critic, poet, author and humorist Gelett Burgess in 1907 on a dust jacket at a trade association dinner. The dust jacket said “YES, this is a “BLURB”!” and featured a (fictitious) “Miss Belinda Blurb” shown calling out, described as “in the act of blurbing”.
Etymology from Wiktionary, CC BY-SA 4.0.