The Colombia international has played in every round of the competition this season and will not lose his place to Arsenal's number one for the big day at Wembley.
Cech, 35, has won the League Cup three times with Chelsea in the past but a winners' medal this year will come as part of Arsene Wenger's squad rather than in a starring role.
"At the start it was clear that it was going to be like that," he said when asked if Ospina would play in the final.
"I will be there with the team supporting but I don't expect to play. It is always hard to watch any game from the bench or even from the stand if you are not selected.
"As a player you always want to be involved but obviously you are in a professional club where there are 25 top players and the manager always makes his choices for the game and you need to accept that."
Ospina has also been playing in the Europa League campaign this season and captained Arsenal as they ran out comfortable 3-0 winners against Ostersund in Sweden last week, saving a last-gasp penalty from the hosts.
The second leg of that tie is on Thursday and Ospina may be one of only a handful of players in with a shout of retaining their place as Wenger shifts focus onto City.
The 29-year-old moved to the Emirates Stadium from Nice in 2014 but has never established himself as Wenger's first choice despite the Frenchman labelling him 'world-class' on several occasions.
His chances to impress have been few and far between but he insists he is always ready to step in when required.
"Going to Wembley is special, the atmosphere and the occasion is special," he told Arsenal's matchday programme.
"I'd like to play every week but I respect the manager's decision. It's tough when you can only select one keeper for a game.
"You have to prepare as though you're going to play every game. It can be tough to play maybe a couple of games a month, especially when they are as big as this one.
"You just need to focus and be ready. I have a very good relationship with Petr, and that helps."