The 32-year old, signed from Aston Villa last July by Martin O'Neill, figured 28 times in his debut campaign for the Black Cats before a host of new arrivals left him down the pecking order.
Summer signings Modibo Diakite and Valentin Roberge have added to the likes of John O'Shea and Wes Brown for competition in defence, but Di Canio says that Cuellar remains in his thoughts.
"Although I have not used him yet, Carlos still has a part to play," he told the Sunderland Echo.
"I have got five centre-backs, which gives me a lot of options and I choose the combinations for different reasons. We need a mixture.
"I want us to bring the ball out from the back and for that we need players who are comfortable passing with both feet, which Diakite and Roberge are, and that's why I picked them ahead of Carlos against Arsenal.
"Diakite is a competitor, he is a good challenger. Roberge played well and, when he came out from the back, he passed the ball out of defence. He also has aggressivity.
"I prefer to play with these two, Diakite and Roberge, because they can communicate together better, because they both speak French.
"And I gave the captain's armband to Diakite when O'Shea was missing because I can speak to him in Italian. But I have to say the season is long, and Carlos will get his chance."