The Belgian, a £6m summer signing from Olympiacos, expressed his delight after making his first start as the Blues maintained their 100% record this season.
"I really enjoyed it and could not be happier," said Mirallas. "It was a dream debut to score two goals and was a night I will remember."
The 24-year-old admitted that he is still some way sort of full fitness and is unsure if he will feature against West Bromwich Albion on Saturday.
"That was only my fourth game, including my pre-season, so I am a long way from peak condition and there is a lot more to come from me.
"Training has been tough but I am getting there. I am tired after the 90 minutes [against Orient]. Hopefully I can play some part this weekend but the manager will know when it is the right time for me to start."
The draw for the League Cup third round will be made later tonight.