Since joining in January, Edwards has played every minute in the Championship and FA Cup after making his debut as a substitute.
The Saints hope he’ll be a key player next season, with Cifuentes praising his impressive impact so far.
“Ronnie has been doing well and performed well last week. I was pleased with that. He came in when we really needed a centre half," Cifuentes said.
"Steve Cook and Liam Morrison did very well and came back quicker than perhaps we anticipated which is a credit to them and this will only benefit our squad.
“I have liked Ronnie for a while. He did well last season with Peterborough United and is the type of defender I like.
"The club did well to bring him in. It has been a win-win situation for both us and Southampton.