The AP said Clinton won the contest two days after voters went to the polls. Previously, the result had been too close to project.
Sanders told AP he will not request a recount. "I prefer to save the taxpayers of Missouri some money," he said.
Missouri remains too close to project for the Republicans, where Cruz and Trump each have 41 percent of the vote. They were separated by 1,726 votes with 100 percent of precincts reporting and 99 percent of the vote in, according to data from ABC News.
According to vote data, Clinton beat Sanders by 1,531 votes, amassing 50 percent of the vote to Sanders' 49 percent.
They were tied in the pledged delegate allocation, with both receiving 32. However, Clinton also received the support of 12 superdelegates, or unpledged delegates.
This is the 18th contest Clinton has won during the primary season.
Michael Briggs, a spokesman for the Sanders campaign, emphasized the fact that Clinton and Sanders almost split the delegates evenly in Illinois and Missouri, and is looking ahead to the rest of the primary calendar.
"He's taking the contest all the way to the Democratic National Convention in Philadelphia," Briggs said.
--ABC News' MaryAlice Parks contributed reporting.