The club had to look for a new backer after sponsors all:sports went into administration in September.
The four-and-a-half-year package is the largest in the club's history, with an option to extend the contract until 2013, depending on Charlton's success.
The new deal will see Charlton shirts sporting Llanera SL's logo.
The club recently had to ban the sale of replica shirts with the all:sports logo on them.
all:sports was taken over by JD Sports but Charlton was unable to reach an agreement with the new company.
