Bird-Smith began to take part in senior competitions towards the end of 2011 and on his international circuit debut at the Gran Premio Cantones de La Coruña, ending the race in 13th place. His debut in the 20 kilometres race walk event came in December and he recorded a time of 1:26:38 hours. He bettered this on the 2012 IAAF World Race Walking Challenge circuit, setting a time of 1:23:15 hours in Taicang. He ranked 43rd in the senior 20 km race at the 2012 IAAF World Race Walking Cup before winning his first national title in August.