Porter, who just completed his first year on the LSU staff, will continue to coach the Tiger running backs, while also playing a key role in the school's recruiting efforts.
"Larry is a vital member of this staff and he's very deserving of this promotion," Miles said. "As the assistant head football coach, Larry will assist me in a variety of administrative matters as well as being involved in many day-to-day duties of running this football program."
Porter came to LSU in January of 2005 after serving on Miles' staff at Oklahoma State for three years.
Porter, who capped his playing career as the fourth-leading rusher in Memphis history, has also coached at Tennessee-Martin and Arkansas State.