Los Blancos have won the competition 13 times but an underwhelming start to the LaLiga season has hardly served to inspire confidence they can claim a 14th title in 2020-21.
Madrid are third in LaLiga, a point behind early leaders Real Sociedad having slumped to a 1-0 home loss to newly promoted Cadiz last time out.
Zinedine Zidane's side failed to reach the quarter-finals last season, losing in a two-legged last-16 tie to Manchester City with a five-month interval between the games due to the suspension of football amid the COVID-19 crisis.
Drawn in Group B with Inter, Borussia Monchengladbach and Shakhtar Donetsk, history is firmly on the side of Madrid progressing to the knockout stages.
Madrid have made it through all 28 of their Champions League group stages and Courtois has every confidence in their ability to go all the way once more.
"I'm sure we can win this Champions League," Courtois said ahead of Wednesday's meeting with Shakhtar.
"Real Madrid are always favorites in this competition. I'm pretty sure, I'm confident we have enough quality in the team to win this title.
"I mean we're not the number one favorites, there are many teams in the hat but we're definitely a candidate for the title.
"Juve, Bayern, Barca, there are a lot of good clubs, it's the most attractive competition in the world and we're going to do all we can to win the title."
Madrid will be heavy favorites to beat Shakhtar having won each of their meetings with the Ukrainian side in the 2015-16 group stage.
However, Shakhtar are unbeaten in their last three Champions League away games under coach Luis Castro.