Viewers across the UK were faced with pixelated screens or unable to access its TV channels while some reported gargled audio and complete blackouts.
The interruptions began at about 3pm and lasted 45 minutes, the broadcaster said.
The broadcaster confirmed the problem has now been fixed but did not reveal the cause.
A total 88 per cent of problems were reported on live channels with 11 per cent experienced via the website and one per cent felt via the app, according to Downdetector.
An ITV spokesperson told the Evening Standard: “We apologise for the reduction in picture quality experienced by viewers watching ITV on Freeview this afternoon. Service for these viewers has been restored.”
Viewers from London, Kent, Middlesex, Essex, Hampshire, Bristol, Greater Manchester and Yorkshire were among those to report difficulties.
One person tweeted: “ITV it’s nice that you’re keeping your viewers so well informed about the lack of channel reception. Not.”
Another person said: “ITV what’s up with all the ITV channels? Have sound, no picture. HD channel 3 ok #itvdown.”
— Hannah Brooks (@hanbrooks) October 11, 2021
Freeview also recognised the issues while responding to a viewer on Twitter.
Its official account said: “We are aware of issues with ITV channels just now. We do not have any more info as yet. We do recommend not retuning.”
It comes after thousands of viewers faced technical issues between 12 and 5pm on Sunday with viewers reporting that their screen was freezing or pixelated with poor sound quality.
This is not the first big broadcaster to experience technical issues in recent weeks.
Thousands of viewers reported difficulties with the main channel, Channel 5 and subsidiaries including e4, 4more and 4music.
Channel 4 apologised for the issues.