Since Marc Wilmots took charge, Chelsea goalkeeper Thibaut Courtois - currently on loan at Atletico Madrid - has been first choice.
But Mignolet is set to be given his chance in the games with Colombia and Japan.
"Simon has proved he has an excellent mentality, something he showed the last few months," said Wilmots.
"He deserves this chance. Thibaut Courtois will remain first choice, though. But if he gets injured, I want to be sure I've an excellent back-up."
Mignolet made his international debut in March of 2011 against Austria and has 13 caps.