From Heiloo, Smit joined the academy at AZ Alkmaar at nine years-old in 2015. He then became the youngest member of their under-12 squad.[2] After progressing through the ranks at AZ, he signed a three-and-a-half-year professional contract in January 2021.[3][4]
In December 2022, Smit was included with the first team squad on their mid-season break travelling training party to Valencia, Spain.[5] In January 2023, a goal Smit scored in a five-a-side indoor game went viral due to its unusual nature, as he beat the outrushing goalkeeper with shot rebounded from the side wall.[6][7][8] Later that month, Smit made his professional debut for Jong AZ in the Eerste Divisie in a home match against Helmond Sport, on January 23, 2023.[9][10]
With AZ under-19s playing in the UEFA Youth League he was part of the team that beat Barcelona and Real Madrid on consecutive rounds to reach the semi-finals in March 2023.[11][12][13] Smit scored a long range goal in the UEFA Youth League last-sixteen tie against Barcelona that brought praise.[14][15][16] He also played in the UEFA Youth League final against Hajduk Split as AZ ran out 5-0 winners.[17]
He made his UEFA Europa League debut for AZ Alkmaar on 7 November 2024 in a 3-1 home win against Fenerbahçe, scoring the second goal and being credited with an assist for the third.[18]