The new deal, agreed with the Office of Rail Regulation, means the firm can continue operating services between King’s Cross and Bradford and King’s Cross and Sunderland until 2026.
The agreement will allow Grand Central Rail to make significant investment in its rolling stock and invest in passenger facilities at local stations.
The West Riding service to and from Bradford Interchange also stops at Halifax, Pontefract Monkhill, Wakefield Kirkgate and Doncaster.
Grand Central managing director Richard McClean said it was excellent news for passengers and staff and “highly significant” for the wider rail industry.
He added: “Not only does this mean we can continue to operate services connecting Sunderland and Bradford to London King’s Cross but we are also in a position to proceed with significant investments to improve our services and encourage future economic growth.
“For many of the towns on our routes we operate the only direct service to London, so this extension is a big coup for those communities and local businesses as well, who can continue to make connections to the capital.
“Our new access rights give us the opportunity to make significant investment in the rolling stock to improve reliability.
“We’ll also work with stations along our route to improve facilities like car parks.”
Councillors in Mirfield have campaigned for a bigger car park and better access for disabled people for several years.