The 25-year-old is currently the longest serving member of the squad and has been with Matsatsantsa for well over a decade, starting in their academy in 2005.
United CEO Stan Matthews expressed his delight at having extended the contract of a player that has been in the first team set up since the 2011/12 season.
“This is the first time we have given a player a straight 5-year deal and Ronwen thoroughly deserves it," he said in a club statement.
"He has worked his way through the ranks from the age of 12 putting in many years of hard work in our academy and now in our first team.
"In a day and age where player loyalty is a rare commodity we are delighted to reward Ronwen for his dedication and excellent performances at the club both on and off the field of play.”