The all-woman W Series cancelled its remaining three races in the United States and Mexico for financial reasons on Monday and declared Britain's Jamie Chadwick champion for the third season in a row.
The series had been due to support Formula One at next week's U.S. Grand Prix in Austin, Texas, before ending its season with two races at Mexico City's Autodromo Hermanos Rodriguez at the end of the month.
"Due to recent unforeseen circumstances outside of W Series' control, we had not been in receipt of contracted funds due to us," W Series founder and chief executive Catherine Bond Muir said.
"Therefore, we have been forced to make the unfortunate decision not to complete our scheduled calendar this season."
Bond Muir said she remained positive about the long-term future of the series and wanted to remain on the F1 support programme.
"We've just had to call it because obviously there are deadlines on payments and things that need to be done... we just had to make a pragmatic call today," she told reporters.
"Going forward, the big message is that I am extremely confident that W Series will be here next year."
Chadwick was 50 points clear of Dutch rival Beitske Visser at the top of the standings after seven races.
W Series, which is free to enter, had net liabilities of £7.5 million ($8.27m) as of the end of last year, according to statements filed with Companies House.
The series started in 2019 with the aim of getting a woman racer to F1.