Revenues in April jumped by 68%, said the broadcaster, but May is expected to rise by 85% with June even better albeit slightly.
ITV added it now expects first-half ad revenues will be up around 26% compared with the same period in 2020.
Carolyn McCall, chief executive, said 2021 had started well with a strong end to the quarter to end-March.
“We have made a good start to 2021 with total revenue and total viewing both up, despite the continuing impact of the pandemic.
“We finished the quarter strongly with the substantial majority of our shows back in production and a recovery in the advertising market.”
In the first quarter, total revenue rose by 2% to GBP709mln (GBP694mln) even with the impact from COVID-19 restrictions.
Studios revenue was up 9% at GBP372mln (2020: GBP342mln), while media and entertainment was 3% lower at GBP484mln reflecting a 6% fall in total advertising.
ITV total viewing was up 1% driven by the Saturday schedule, which included Unforgotten, Saturday Night Takeaway and the Six Nations, and by soaps during the week.
The importance of Love island to the schedule was illustrated by the impact of its absence on online viewing figures in January and February.
They dropped by 11% but excluding the impact of Love Island, online viewing was up 23% in the first quarter.
ITV main channel’s share of viewing rose from 17.9% to 18.2%
Streaming joint venture BritBox International’s rollout is on track with a launch in South Africa this summer and continued growth in subscriptions across the US, Canada and Australia said the statement.