Indigo was able to restore systems in a very short span of time with minimal impact, it said.
IndiGo on Thursday said that its servers were hacked during the early days of December and it is possible that hackers might upload some internal documents on public websites.
"We would like to make this disclosure that some of our servers were subject to a hacking incident earlier this month," said India's largest airline in a statement.
Indigo was able to restore systems in a very short span of time with minimal impact, it said.
"There were some segments of data servers that were breached - so, there is a possibility that some internal documents may get uploaded by the hackers on public websites and platforms," the airline said.
The carrier said it realises the seriousness of the issue, and it continues to engage with "all relevant experts and law enforcement" to ensure that the incident is investigated in detail.