[1] Simarjeet made his List A debut for Delhi in the 2018–19 Vijay Hazare Trophy on 20 September 2018.
[3] He made his Twenty20 debut on 11 November 2019, for Delhi in the 2019–20 Syed Mushtaq Ali Trophy.
[4] In June 2021, he was named as one of five net bowlers for India's tour of Sri Lanka.
[5][6] Following a positive case for COVID-19 in the Indian team, Singh was added to India's main squad for their final two Twenty20 International (T20I) matches of the tour.
[8] In February 2022, he was bought by the Chennai Super Kings in the auction for the 2022 Indian Premier League tournament.