The 2017–18 Ranji Trophy was the 84th season of the Ranji Trophy, the premier first-class cricket tournament that took place in India between October 2017 and January 2018. Vidarbha won the tournament, beating Delhi by 9 wickets in the final, to win their first Ranji Trophy title. Vidarbha made their Ranji Trophy debut in the 1957–58 season, making it the third-longest wait before a team won their maiden title. Vidarbha's captain, Faiz Fazal, said that "winning the Ranji Trophy has been the biggest achievement in my career".

The Delhi cricket team is a first-class cricket team based in Delhi, run by the Delhi & District Cricket Association, that plays in India's first class competition, the Ranji Trophy, limited-overs Vijay Hazare Trophy and Syed Mushtaq Ali Trophy. They have won the Ranji Trophy seven times and have been runners-up eight. Their latest title in 2007-08 came after a long wait of 16 years. The previous win was in the 1991–92 season when they beat Tamil Nadu in the final. The team's home ground is Arun Jaitley Stadium.