Ripon is battling for honours in the large town category, Starbeck in the urban community section and York has its sights trained on the city category title.
The results will be announced at a ceremony in October. Finalists will vie to win the Champion of Champions category which, last year, was taken by Broughshane, County Antrim.
Councillor Sonja Crisp, cabinet member for leisure, culture and tourism for City of York Council, welcomed the news for York.
She said: “To be in the national finals for the second time in three years is testament to all the hard work that goes on throughout the year in York by everyone including local residents, voluntary groups, businesses, and communities of interest to improve the look of York.
"We know from the many compliments we get about our floral displays that they are appreciated by residents and visitors alike.
"But, In Bloom is more than flowers: at the heart of the competition are the local efforts working together to improve and be proud of their part of the city.”
Andrea Van Sittart, head of regional development with organisers, the Royal Horticultural Society, said; "Thanks to the legacy of London 2012, the power of volunteering has never been more widely-recognised or appreciated. Britain in Bloom saw a 30 per cent uplift in sign-ups over the past year and this year we have a record number of finalists."