Sims graduated to Formula E after years as a BMW works driver in GT racing, where he raced with his former teammate Antonio Felix da Costa.

Starting his racing career in karts in 1998, Sims went on to clinch the McLaren Autosport BRDC Award for promising young British drivers ten years later. The following year, the British driver progressed to Formula 3, where he started to combine single-seater driving with GT and sportscar racing in series such as Blancpain Endurance, British GT and 24 Hours of Le Mans.

Making his debut in the ABB FIA Formula E Championship ahead of the 2018/19 season for BMW i Andretti Motorsport, the British driver set the fastest times during pre-season testing for two out of the three days. With a self-declared interest in renewable energy and electric cars, Sims is well placed to race for a manufacturer that prides itself on it's hybrid and all-electric cars.

After a successful debut season, which saw the Brit clinch his first podium in the all-electric series in the final race of the 2018/19 season, Sims continued with BMW for a second season, this time alongside Maximilian Guenther. The Brit recommenced his rise in the all-electric with a streak of Julius Baer Pole Positions in Diriyah and his debut win around the desert circuit.

For 2020/21, Sims jumps across to Mahindra Racing to spearhead the Indian manufacturer's goals of becoming Formula E's first-ever World Champions.