From 29 October, the New York-based airline will add a second daily departure from Gatwick to JFK at 14.00, two hours after the current midday flight. The new frequency will leave New York at 21.59, arriving at 10.22.
In addition, the carrier has acquired a permanent second daily slot at Heathrow, for which it currently relies on a leasing deal with Qatar Airways.
The new arrangement commences on 30 October, when the JFK flight will depart at 10.45, later than the current 08.25 departure. The return to the UK will be at 21.02, arriving at 09.30.
JetBlue is also going ahead with previously-announced plans to launch Gatwick-Boston on 5 August and Heathrow-Boston on 21 September.
The airline’s chief executive Robin Hayes said: “The US-UK air corridor is among the busiest in the world and to effectively compete JetBlue is adding more flights across the North Atlantic, growing from just one daily flight last summer to five by this autumn.
“And with permanent slots at Heathrow – the highest in-demand slots globally – we’re now positioned to provide long-term service at one of the busiest airports in the world.”