Sunderland's rail operator Grand Central started its fourth service to King's Cross today.
Managing director Tom Clift said: "We are very excited about the extra trains."
The company has leased two 10-year-old Class 180 trains for the fourth service and has spent the last few months preparing and testing the new rolling stock and training crews.
The new daily Monday to Friday service will leave Sunderland at 9.18am, calling at Hartlepool at 9.42am, Eaglescliffe 10.01am, Northallerton 10.19am, Thirsk 10.28am, York 10.52am and London King's Cross at 12:50pm.
The return journey leaves King's Cross at 7.18pm, calling at York at 9.21pm, Thirsk 9.39pm, Northallerton 9.50pm, Eaglescliffe 10.10pm, Hartlepool 10.29pm, arriving in Sunderland at 10.54pm.
Slightly different times will apply on the Saturday service.
Rail watchdog The Office of Rail Regulation said in January it was minded to approve Grand Central's application to run a fourth service between Wearside and London and the formal go-ahead came in February.
The changes are intended to make Grand Central a more attractive option for leisure and business travellers.
At present, trains leave Sunderland station at 6.41am or passengers must wait until 12.30pm for the next train, while the last return service departs King's Cross before 5pm.
"This new service makes the timetable so much more attractive," said Mr Clift. "We will have a later returning service, which means business people don't have to rush for the 16.50.
"And the train to London at 9.18 in the morning is great for a day out in London or York."