During the 2022 Indian Premier League auction, he was acquired by the Kolkata Knight Riders. In a match during this year's tournament on April 9, 2023, Rinku set a record-breaking performance. He hit 5 sixes in the final over against the Gujarat Titans, successfully chasing down 29 runs - marking the highest-ever chase in the IPL's last-over history.
During the 2018–19 Ranji Trophy group stage, he emerged as the top run-scorer for Uttar Pradesh, amassing 803 runs across nine matches.By the end of the tournament, he totaled an impressive 953 runs from ten matches.
He marked his international debut in August 2023 during the first T20I against Ireland at The Village. Later, on November 26, 2023, he showcased a stellar performance, scoring an unbeaten 31 runs from just 9 balls against Australia in the second T20I held at Thiruvananthapuram.
Rinku Singh, batting at an unbeaten 68 runs off 39 balls, unleashed a massive six on the fourth delivery of the 19th over against Aiden Markram. The colossal shot sailed between long-on and mid-wicket, crashing into the glass panel of the media center in Gqeberha, shattering it completely. The stunning visuals of this incident have since gone viral.