On 14 November 2022, Maukonen signed his first professional contract with his hometown club FC Lahti on a three-year deal, at the age of 15. Maukonen made his debut in Veikkausliiga with FC Lahti on 3 June 2023, after being named in the starting line-up against Ilves. Maukonen became the youngest ever goalkeeper to debut in the highest level in Finland, at the age of 16 years, 3 months and 19 days. He also became the first player born 2007 to debut in the league. His contract was extended on 8 October 2024 until the end of 2026.