The season started on 29 April 2017 and ended on 21 October 2017.
[1] The winning team qualified directly for promotion to the 2018 Veikkausliiga, while the second had to play a play-off against the eleventh-placed team from Veikkausliiga to decide who would play in that division.
A total of ten teams contested in the league,[2] including seven sides from the 2016 season, and FC Honka and Gnistan who were promoted from Kakkonen after winning the promotion play-offs.
PK-35 Vantaa, who were relegated from Veikkausliiga, declared bankruptcy and withdrew their spot from the league.
JJK, the champion of 2016 Ykkönen, was promoted to the 2017 Veikkausliiga.