The 25-year-old joined the Shrimpers in the summer after a trial, having not played a first-team game since November 2014 while at Blackpool.
The former Newcastle and Swindon forward has since scored twice in nine Southend appearances.
Phil Brown's side are undefeated in any match Ranger has started, winning five and drawing three of the eight games.
Southend United striker Nile Ranger has signed a new three-and-a-half year contract with the League One club.