The line is owned by a group of private investors.
The ORR ordered it to lower access charges after carrying out a review of the company’s latest spending plans.
It stated: “The company is being directed to reduce its charges for renewing its track assets and its stations, including St Pancras.
“ORR was able to identify specific areas in the company’s spending plans where further improvements can be made, resulting in savings to passenger and freight train operators.
“ORR’s view is that better management of the track and station assets can result in lower charges, ultimately benefiting customers.”
Feras Alshaker, the ORR’s director for planning and performance, said: “Our review of HS1 Ltd’s spending plans has resulted in significantly lower costs for train operators.
“Although HS1’s original plans were good, the company must now change specific areas of those plans to account for our decisions.”
HS1 Ltd chief strategy and regulation officer, Mattias Bjornfors, said: “We are pleased to see the ORR’s positive endorsement for our plan for the next five years.
“Our plan for 2025-2030 includes proposals to enhance efficiency and reduce the cost of operating the high-speed line, incorporating innovations like track deterioration modelling to better target renewal investments.”