The extension is for five guaranteed years with a club option for a sixth and seventh year and includes $23 million in guaranteed money, Heyman reports.
Jeff Passan of Yahoo Sports reported earlier that the two sides were discussing an extension.
Over 183 innings last season, Ventura posted a 3.20 ERA with 159 strikeouts and 59 walks. The 23-year-old also pitched 15 1/3 innings in 2013.
Ventura, who initially signed with Kansas City for only $28,000 in 2008, is known for his high pitch velocity. He is a native of the Dominican Republic.