"Marco won a lot of delegates tonight," Rubio’s presidential campaign communications director Alex Conant tweeted. "DC's changed a lot in last decade. It's a minority-majority city that's embracing the future. And today voted for it."
Rubio won 37.3 percent of the votes and secured the support of 10 delegates. He was trailed by Kasich with 35.5 percent of votes and nine delegates.
US Republican nomination frontrunner Donald Trump and Texas Senator Ted Cruz came third and fourth respectively, which did not translate in any delegates for them.
Contenders for the Republican nomination are vying to win delegates who will then vote for them at the GOP convention in July, ahead of the November presidential election.