The upgrade is based on lower debt levels, strong results and updated financial targets, according to Securitas.
Previously, the rating was BBB.
A higher credit rating can make borrowing easier and push down interest rates on loans, as it means that more investors, according to their guidelines and risk calculations, can bid on the company's bonds.
Securitas' share, which is up 2.6 percent, has not moved significantly after the announcement of the rating upgrade.
