[13][14] On 15 September 2014, the club signed Nicolas Anelka, a former French international who had been a free agent since his departure from West Bromwich Albion earlier in the year.

The club then roped in India's captain Sunil Chhetri for a domestic record-breaking deal of ₹1.2 crore,[23] and signed 2015 I-League's player of the year awardee Sony Norde of Haiti.

The club also signed 2010 FIFA World Cup Golden Ball winner Diego Forlán on a three-month deal, with the option to extend for another year as a marquee player for the season.

Forlán scored the first hat-trick of the Hero ISL 2016 season as The Islanders beat Kerala Blasters 5–0 at Mumbai Football Arena on 19 November 2016.

[32] In the foreign department, they retained the defensive duo of Goian and Gerson Vieira,[33] alongside Brazilian midfielder Leo Costa.

[35] However, the club's new signings did not perform at their best, as they finished the season in 7th position, failing to qualify for the playoffs, with the coach being criticized for overly defensive tactics.

[38] After the announcement that Mumbai City FC had parted ways with Guimarães, the Islanders broke the news about their new head coach.

[39] The club also signed Indian Internationals Alen Deory and Subhasish Bose along with some foreign players such as Modou Sougou, Rafael Bastos, Arnold Issoko and Paulo Machado.

[41] They also managed to break league leaders Bengaluru FC's unbeaten run at Mumbai Football Arena in January.

[43] The next task for Jorge Costa and his side was the 2019 Super Cup, with the Islanders drawn to play Chennaiyin FC in the Round of 16 on 29 March at the Kalinga Stadium in Bhubaneshwar.

After finishing fifth, and with the City Football Group ownership coming into full effect, Jorge Costa's reign at the club ended.

Under the new ownership, the club decided to kickstart a new era and signed the former FC Goa coach Sergio Lobera as manager.

[3] The club signed Hugo Boumous from FC Goa after paying a release clause of ₹1.6 crores, a record fee in Indian football.

During the first phase of the league, Mumbai City FC got 25 points from the first ten matches, which included eight wins, one draw, and one loss.

In their final against ATK Mohun Bagan at the Fatorda Stadium, they won the game 2–1, with Bipin Singh scoring the decisive goal in the 90th minute.

Thus, Mumbai City FC became the first club to win the league winners' shield and the ISL trophy in a single season.

On 8 October 2021, Mumbai City appointed English manager Des Buckingham as head coach on a two-year contract.

Ahead of the 2022 AFC Champions League kick-off, the club went to Abu Dhabi for training and defeated Emirati giants Al Ain 2–1 in a friendly match.

[52] Under Buckingham, Mumbai City became the first Indian club to win a match in the AFC Champions League, as they defeated Al-Quwa Al-Jawiya of Iraq by 2–1.

Buckingham was highly credited with improving the performances of young Indian players and for the attractive brand of football that Mumbai played throughout the season.

The club began the 23–24 season with the 2023 Durand Cup, where Mumbai were drawn in a group with Jamshedpur FC, Mohammedan SC, and the Indian Navy football team.

Mumbai went on to win all three games of the group stage, but ended up losing in the quarter-final to eventual winners Mohun Bagan SG on 28 August 2023.

[58] Buckingham's last match as Mumbai manager came on 6 November 2023, in a spririted 2–0 loss at home to Saudi Arabian team Al Hilal.

On 9 December 2023, Petr Kratky was appointed as the new head coach of Mumbai City after Des Buckingham left mid-season to join EFL League One side Oxford United.

In the final, Mumbai took revenge against Mohun Bagan Super Giant, winning 3-1 with goals from Jorge Pereyra Diaz, Bipin Singh, and Jakub Vojtus, securing the second ISL Cup in the club's history.

[68] The first match of the new season was away against Mohun Bagan SG on 13 September 2024, which eventually ended in a 2-2 draw with goals from Tiri and Thaer Krouma.

[69] In the club's next match, away against Jamshedpur FC, despite going 1-0 up following a long-range goal from Nikos Karelis, Mumbai eventually lost 3-2.

[93] The West Coast Brigade is one of the notable fan club of Mumbai City FC, which is known for its support to the team at both home and away matches.

Both clubs played out the first match of the 2024-25 season, ending in a 2-2 draw with Mumbai's Syrian defender Thaer Krouma scoring a last-minute equalizer.

[104] Ahead of the 2024-25 season, with the club opting to conduct pre-season training in Thailand, the reserves contested the 2024 Durand Cup.