The operator said it is adding capacity on routes serving the town between Saturday 20 December 2025 and Sunday 4 January 2026, to meet increased festive demand.
Thousands of additional seats will be made available across the South West network, including extra journeys to and from Swindon.
National Express said the move will also provide an alternative for passengers affected by planned rail engineering works during the holiday period.
More than 9,200 extra seats are being added between the South West and London overall, with the largest uplift on the Bristol to London route.
The company confirmed that services linking Swindon with London and Heathrow Airport will also see increased availability.
The additional services are expected to support Christmas shopping trips, family visits, airport transfers and post-Christmas travel.
Ed Rickard, Network Director for National Express, said:
“With planned rail engineering works ahead, more people are turning to us for affordable, reliable travel and we’ve stepped up once again to add extra seats to ensure customers can get where they need to be this Christmas.”
National Express said its network continues to perform strongly, with punctuality above ninety per cent and cancellations remaining below 0.2 per cent.
Families travelling together can also benefit from free coach travel for up to three children when travelling with a paying adult, with the offer running until Sunday 4 January 2026, subject to availability and terms.
Coaches on Swindon routes include reclining leather seats, luggage allowance of up to twenty kilograms, USB charging points and free Wi-Fi on selected services.
Tickets are already on sale, with passengers being advised to book early as festive services are expected to be busy.
Further information and bookings are available via the National Express website.
