From 1928 onward, Mickey was voiced by his creator. It was a task in which Walt Disney took great personal pride.
However, by 1946, he was becoming too busy with running the studio to do regular voice work, and it’s also speculated that constant smoking had damaged his voice over the years. That’s how veteran Disney musician and actor Jimmy MacDonald became the voice of Mickey.
Walt Disney would come back as the famous mouse for the introductions to the original 1955–1959 run of The Mickey Mouse Club TV series.