R. Kelly — Boots Rowdy Fan from Concert … By Singing!

When R. Kelly saw two ladies fighting over a seat at one of his concerts … he didn”t scream for security — he SANG for security … and it was all caught on tape.

Kelly was in the middle of his show at the Nokia Theater in Downtown L.A. this weekend … when he noticed two female fans getting physical in the crowd.  One source tells us one woman had accused the other of stealing her seat … and they were thiiiis close to trading blows.

And that”s when R. saved the day … stopping his show … and breaking out in song: “SECURITY … SEC-UR-ITY.”

It”s hard to hear exactly what Kelly said after that … but he definitely barked some orders to the crowd control staff and dropped a couple of cuss words … while staying in tune.

Security eventually responded to the situation and escorted one of the women out of the building … thus concluding the most beautiful ejection we”ve ever heard.