Galloway has excelled for the Merseyside club in the left-back role usually occupied by England international Leighton Baines.
"The gaffer told me he wanted to reward me and I was more than happy to commit my future," Galloway told evertontv.
"As soon as I got here I knew this was the place that I wanted to be for a long time. With the aspirations that the Club has for the future, I want to be a part of what's happening here.
"I have loved every minute of being at Everton, the ups and the downs, and hopefully there are plenty more ups to come in the future."
Galloway penned a new deal on Thursday that will keep him at Goodison Park until the summer of 2020.