Khun Vichai was the founder and CEO of King Power Duty Free, an operator of duty-free shops. In December 2009, King Power received the royal warrant from King Bhumibol of Thailand in a ceremony attended by Vichai. He was ranked by Forbes magazine as the 5th richest man in Thailand, reportedly worth US$4.9 billion, as of 28 October 2018.
In August 2010, the Asia Football Investments consortium including Vichai and his son Aiyawatt purchased English Football League Championship club Leicester City. He succeeded Milan Mandarić as chairman of the club in February 2011 while continuing as owner, and Aiyawatt became the vice chairman. In July 2011, the club's formerly named Walkers Stadium was renamed the King Power Stadium.
Leicester City went on to win the 2015–16 Premier League title after starting the season as 5000/1 rank outsiders. Shortly before the 2016–17 season, Vichai gifted 19 players a BMW i8 - at £100,000 each—as a gift for winning the title.
In May 2017, he bought his second football club, OH Leuven in Belgium.