The season was the 48th season of the second-tier club football in Japan and the 21st season since the establishment of J2 League.
Following eight successful seasons, Kashiwa Reysol bid farewell to the first division. A similar fate befell V-Varen Nagasaki, who returned to J2 after their inaugural season in the top tier. Matsumoto Yamaga and Oita Trinita, having earned promotion, filled their vacancies, while Tokyo Verdy missed out on promotion after losing the play-off against Júbilo Iwata. In addition, four teams experienced changes in their league status: Roasso Kumamoto and Kamatamare Sanuki exited J2, paving the way for the newly-promoted FC Ryukyu and Kagoshima United, both set to embark on their inaugural J2 season.
The participating clubs are listed in the following table:
The total number of foreign players is limitless, but clubs can only register up to five foreign players for a single match-day squad. Players from J.League partner nations (Thailand, Vietnam, Myanmar, Malaysia, Cambodia, Singapore, Iran and Qatar) are exempt from these restrictions.
Players in bold are players who join midway through the competition.
<section begin="J2 prorel playoffs" /> In the first two rounds of the 2019 J.League J1/J2 Play-Offs (2019 J1Ã¥ÂÂå ¥ãÂÂ㋼ãªãÂÂ), if the score is tied after 90 minutes, no extra time is played and the winner is the team with the best J2 League ranking. In the final match against the J1 team, if the score is tied after 90 minutes, no extra time is played and the J1 team wins.
<section end="J2 prorel playoffs" />
Shonan Bellmare remains in J1 League.<br />Tokushima Vortis remains in J2 League.
.