His first senior medal came at the 2015 IAAF World Relays, held on home turf, where he gave American competitor Jeremy Wariner a close run in the relay, helping the Bahamas to the silver medal alongside Ramon Miller, Michael Mathieu and Chris Brown. He began to focus on the 400 m in the 2015 season and this proved a successful transition. He rapidly improved to become the youngest Bahamian ever, at 19 years old, to run the distance under 45 seconds, and moved up to fourth on the Bahamian all-time lists with a best of 44.64 seconds. He set the time at the Bislett Games, which brought him victory on his debut on the IAAF Diamond League circuit, finishing ahead of Matthew Hudson-Smith and Pavel Maslák.