Richards' first major competition was the 2012 IAAF World Indoor Championships. There, he ran the third leg of Trinidad and Tobago's 4x400m relay squad, which won the bronze medal. 2017 became a breakout season for Richards; he opened his season with a wind-assisted 19.98, and 16 days later he ran his first legal sub-20 with 19.97 seconds, lowering his personal best by over half a second. He won the national 200, title in 20.15 seconds, allowing him to compete at the IAAF World Championships in London later that year. He also improved his 400m personal best by 7/10ths of a second with 45.27. Richards made his outdoor world championship debut at the IAAF World Championships in London. Competing in the 200m, he ran the fastest time in the heats of 20.05, and the next day he won his semi-final in 20.14 seconds. He then went on to win the bronze medal in the final; Ramil Guliyev of Turkey won gold in 20.09 seconds, while Wayde Van Niekerk of South Africa beat Richards to the silver medal by exactly 1/1000 of a second. Van Niekerk clocked 20.106, while Richards clocked 20.107. Richards stated that his race had been undermined when he slipped coming out of his blocks. "I tried my best not to let it affect me too much," he said. "At the turn I wasn't in contention really, so to get a medal from there is a great achievement." Three days later, he ran the second leg for Trinidad and Tobago in the Men's 4x400m relay, making considerable ground of the USA's Gil Roberts before handing the baton to Machel Cedenio. The team ultimately went on to win gold. In September later that year, Richards announced that he was turning professional, and foregoing his final year of collegiate eligibility; he signed an endorsement deal with Adidas. Despite turning pro, he remains enrolled at Alabama to continue work towards his degree. In March 2018, he competed in the 2018 IAAF World Indoor Championships in Birmingham, as the second leg of Trinidad and Tobago's 4x400m relay squad. Despite being the defending champions, they ultimately came fourth. Richards tried to overcome Poland on the second leg but remained third on the second lap. Lalonde Gordon gave up on the line, giving Belgium the bronze.
