SoftBank finished in first place in the Pacific League during the 2017 regular season, while the BayStars advanced to the postseason after finishing in third place in the Central League. In the 2017 Climax Series, the Hawks defeated the Tohoku Rakuten Golden Eagles to win the Pacific League Championship. The BayStars defeated the Hiroshima Toyo Carp to become the Central League champions, becoming the first Central League team to finish in third place during the regular season to win a Climax Series.
The Hawks won the first three games of the series. Facing elimination, the BayStars won Games 4 and 5. Returning home, the Hawks won Game 6 to win the series, 4–2. Hawks' pitcher Dennis Sarfate, with two saves and a Game 6 win, was named the Japan Series Most Valuable Player (MVP). Toshiro Miyazaki won the Fighting Spirit Award, given to the best player on the losing team. This is the first Japan Series loss for the BayStars, having won in two previous appearances in 1960 and 1998.