[7] He regards his uncle Jugraj Singh as his mentor,[1] and credits him for persuading Hardik to stay back when he decided to move to the Netherlands after opportunities in India seemed to dry up for him as a 18-year-old.

After becoming the vice-captain of the Indian junior team, Singh made his senior international debut at the 2018 Asian Champions Trophy held in Muscat.

Singh's 57th-minute counter-attacking goal helped India secure a 3–1 win, and an entry into the medal-round for the first time since the 1980 Moscow Olympics.

[18] In the next group stage match, against England, Singh sustained a hamstring injury leading him to miss the rest of the tournament.

[19] In July that year, Singh played his 100th match for India, against England, in the 100th Anniversary Spanish Hockey Federation tournament in Barcelona, Spain.

Recognizing his performances in these successes, Singh was awarded the FIH Player of the Year (Male).