They were placed in Group A along with defending I-League champions Dempo, Pailan Arrows, and Shillong Lajong and their matches were played in Jamshedpur.

[3] The tournament did not end well for Mumbai as they lost two of their matches and drew one, finishing with 1 point, 3 goals scored and 7 conceded.

Mumbai began their first I-League game of 2012–13 away from home on 6 October 2012 against Pailan Arrows in which the team lost 3–2.

[6] Mumbai started November with yet another lost as they stumbled to former champions Salgaocar at the Balewadi Sports Complex 1–0 after a 9th-minute goal for Francis Fernandes.

However Mumbai finally won their first match of the season in their fifth attempt as they came back from 2–0 down to win 3–2 on 9 November 2012 at the Balewadi Sports Complex with Gabriel Fernandes, Justin Stephen, and Afghani international Zohib Islam Amiri scoring the goals for Mumbai.

[8] Mumbai then won their second game in a row on 17 November 2012 against Sporting Clube de Goa at the Balewadi Sports Complex Nicholas Rodrigues, Gabriel Fernandes, Justin Stephen, and David Opara providing the goals for Mumbai.

[9] Mumbai then drew their first match of the season in a surprising 1–1 draw on 25 November 2012 with Mohun Bagan at the Balewadi Sports Complex after former Indian international Abhishek Yadav scored the equalizer for Mumbai in the 62nd minute after three-time I-League top scorer Odafe Onyeka Okolie gave Bagan the lead in the 21st minute.

Source: I-League table Note: Flags indicate national team as defined under FIFA eligibility rules; some limited exceptions apply.