Flights departed from Belfast International, Birmingham, East Midlands, Edinburgh, Glasgow, Leeds Bradford, Stansted, Manchester, and Newcastle on Thursday (1 July) to the Balearic Islands and Madeira.
On Friday (2 July), the carrier will launch operations from Bristol to Majorca and Menorca.
The company reported July bookings to the Balearic Islands had increased by 3,000%, with Madeira bookings jumping by around 1,500%.
Steve Heapy, chief executive of Jet2.com and Jet2holidays, said the operator was aware of the "pent-up" demand from customers and agents to travel abroad.
"We have already added extra flights to Madeira to cope with demand," he added. "It is fantastic to be back in the air and doing what we do best."
