Miles admitted: "I am really happy with the move. Obviously I have been playing in National One for three seasons but I have been looking for a bigger club and having watched Ulster in the Magners League and Heineken Cup, I am delighted to be joining the squad.
"Ulster is a big club with big aspirations and high hopes for the upcoming season and I am really looking forward to working with Steve Williams again."
Williams, Ulster's new forwards coach, coached Miles during his time at Pertemps Bees.
Miles will replace Ulster's summer signing Neil Hanna who is unfortunately out for the season after suffering a cruciate knee injury in pre-season training.
Turning 26 in December, Miles represented Wales at Under-21 level and following a short training stint, will be available for selection for the Ulster-Gloucester game next weekend at Ravenhill.