The charm was invented by Felix Summerbee during the 1400s.
Professor Flitwick taught Harry Potter, Ron Weasley and the rest of the class the charm in Harry's third year. Hermione Granger missed it due to distractions by Draco Malfoy's bullying. This distressed her greatly, as she suspected Professor Flitwick might test them on the charm in their end-of-year exams, and she was right. Later that year, the third year students, including Harry, Ron and Hermione were indeed tested on the Cheering Charm during their exams. Harry very much overdid his and Ron (his partner) had to be led away to a quiet room.
The written Charms O.W.L. in 1996 included a question about Cheering Charms.