Hannola signed his first contract with RoPS in October 2016, 13 days before his 15th birthday.[2] He made his debut in the 2017 Finnish Cup in January 2017. He scored his first senior goal in the same competition, the second of a 9–0 victory over Oulun Palloseura.[3] He made his league debut in April 2017, coming on as a 90th minute substitute for Saku Ylätupa in a 3–1 victory over PS Kemi.[4]
Midtjylland
In early 2017, it was announced that Hannola would be joining DanishSuperliga side FC Midtjylland in the summer.[5][6][7] He signed a new three year deal with FC Midtjylland in June 2018, and was assigned to the club's academy squad.[8]
HJK and SJK
After playing the 2021 season for SJK on loan from HJK Helsinki, on 5 April 2022 Hannola returned to the club on a permanent basis with a long-term contract, for an undisclosed fee, reported to be €80,000.[9] On 3 August 2024, his deal was extended until the end of 2026.[10]
International career
Hannola has represented Finland at the under-16 and under-17 level.[11][12] He made his debut for the under-21 squad in June 2021.[13]