Born the third child of Beverly Walcott and Endy King, Walcott grew up playing football and cricket, striving to keep up with his athletically talented older brother Elton. He was raised in the fishing village of Toco, in north-east Trinidad. He did not take up the javelin until the age of 15, but found immediate success. By April 2009, one week after his 16th birthday, he was the Caribbean youth champion. In 2010 he stepped up to the standard regulation javelin, and he continued his domination of the Caribbean junior division, as the three-time winner in the Junior javelin throw at the CARIFTA Games in 2010 to 2012, setting a new NACAC North, Central American and Caribbean junior record in 2012.
2012 World Junior Champion
He began the Olympic year in April with his fourth-consecutive victory at CARIFTA Juniors. A record throw of earned him the distinction of competing unbeaten throughout his CARIFTA career. In late May 2012 he twice improved his personal best, breaking through the 80-meter mark for the first time. At the Quantum Classic in Trinidad and Tobago he threw, breaking Trinidad's national javelin record of, set in 1996 by Kurt Thompson. It was also a NACAC junior record as well. One week later he reset all those marks, while competing at the IAAF International Centennial Meet in Havana, Cuba. He extended the records with a winning throw of.
In the stadium on Saturday evening 11 August, made conditions for the javelin throw less than ideal, and worse than during Wednesday's qualifying rounds. Walcott responded to the pressure of the Olympic finals by throwing a personal best distance on his first throw, giving him the lead, and then exceeding that distance on his second throw. He won the Olympic javelin gold medal with a throw of 84.58m. He defeated a string of top athletes to win the competition including 90-metre thrower Tero Pitkämäki and two-time defending Olympic champion Andreas Thorkildsen, as well as Veselý, Oleksandr Pyatnytsya and Antti Ruuskanen. This made Walcott the youngest-ever Olympic champion in javelin throw and the second non-European to win the Olympic gold in men's javelin throw since American thrower Cy Young in Helsinki in 1952. Steve Backley, a former three-time Olympic medalist in the javelin remarked that it was a "surprise win for Keshorn Walcott. Everyone else struggled with the wind". Following his Olympic victory, Walcott was hailed as a national hero. On 13 August, the day of his arrival back in Trinidad, was declared a national holiday. He was awarded $150,000 in cash and given land near his hometown of Toco, as well as a luxury home in Port of Spain. In addition, both the Toco lighthouse, and the Toco Secondary School were renamed in his honour. Walcott has been coached since 2009 by Cuban-born Ismael Lopez Mastrapa.
2013 to 2014
Walcott's 2013 season was hampered by injury. In his first competition since his Olympic victory, he "opened big", nearly matching his personal best with an opening round throw of at a hometown meet in Hasley Crawford Stadium in Port of Spain, Trinidad, on Friday 3 May. In an early March 2014 interview with BBC Scotland, Walcott said that after some rest his ankle "is back to normal". With no World or Olympic competitions to aim for, his 2014 season will be targeted on the 2014 Commonwealth Games, to be held in Glasgow, Scotland. He had a six-week training camp in Cuba in March and planned to compete at a few events in May 2014, before taking part in another training camp in Europe so he can adjust to Glasgow's climate. He said, "My coach likes me to get away from a lot of distractions and just focus on training and being healthy." In the qualifying round of the 2014 Commonwealth Games, Kershorn threw a new personal best of on 1 August, but in the finals on 2 August he finished second with a throw of 82.67m, trailing Julius Yego of Kenya's winning 83.87m. At the IAAF Diamond League's final meeting, the Weltklasse in Zurich, Switzerland on 28 August 2014, he set a new personal best/national record of 85.77m in the opening round, finishing second behind Germany’s Thomas Rohler's toss of 87.63m.
