Happ and the Cubs have agreed to a $3 million signing bonus -- just under the $3,351,000 slotted for his spot as the No. 9 overall pick.
The Cubs have not confirmed the deal, which is pending a physical.
Happ became the highest University of Cincinnati player drafted -- the program had never had a player taken in the first two rounds -- after being named a 2015 Golden Spikes Award semifinalist and a unanimous All-America.
This year for the Bearcats, he led the team with a .369 average and belted 14 home runs, 18 doubles and 44 RBIs.
Joey Nowak is a reporter for MLB.com. Follow him on Twitter at @joeynowak. This story was not subject to the approval of Major League Baseball or its clubs.