Dundee services currently fly into London City while Derry flights operate to Stansted. These will shift to Heathrow Terminal 2 early next month.
Single-ticket connections from Derry through Heathrow range to 119 destinations across 56 countries, while from Dundee there are 97 options across 45 countries.
In addition, Scottish island services via Dundee – from Kirkwall airport in the Orkney Islands and Sumburgh airport in the Shetland Islands – will also now fly into Heathrow.
Loganair described the shake-up as "the largest single expansion of regional, domestic air connectivity at Heathrow in a generation".
The Derry service will switch to Heathrow from 6 May with the three services from or via Dundee due to switch on 7 May.
"The move to Heathrow truly is a game changer for UK regional air services,” said Loganair chief executive Jonathan Hinkles. “Alongside excellent ground transport links into central London, the new range of global flight connections will bring new inward investment opportunities and tourism into the UK’s regions, together with enabling travellers to use their local airport to fly worldwide for the first time."
Loganair’s Derry and Dundee services are operated as part of a public services obligation (PSO) agreement, changes to which typically require sign off from the transport secretary. The carrier confirmed last month it had secured 30 additional slots at Heathrow as part of a lease agreement with British Airways.
All routes will be operated using Embraer 145 and ATR42 aircraft, and will be staffed by locally based crew from Derry and Dundee.
Future bookings to and from either London City of Dundee have been safeguarded, said Loganair, with passengers having already been informed of the change in London terminus.
Morning flights will now leave Dundee at 7am with evening flights returning at 6.50pm. Morning flights will also now leave Derry at 6.35am rather than 6.50am.
