The 26-year-old South Korea international has featured just three times for Hoops this season, with a last appearance on November 28 in a 1-0 win over Leeds, frozen out by Paul Konchesky and more recently the return of Jack Robinson from injury.
"Yun is a player that will bring us some of the experience that we need in our situation," Addicks boss Jose Riga told the club website.
"He knows the Championship and has a good knowledge of English football."
Suk-Young has scored one goal in 37 appearances for Rangers since joining from Chunnam Dragons in January 2013, but has found the physical demands of Championship a test.
However, he can't lose by getting games with Charlton. If he adds anything that helps a side in deep trouble, he will get the credit. If it doesn't work out, the Addicks were in the deep mire long before he arrived.
Yun's wages will also be offset by the south Londoners and with the player out of contract at the end of the season it will put him in the shop window for a future deal elsewhere.