Reynolds, who also pitched in high school, is an interesting prospect because he has left-handed power and is athletic at his size to play both corner outfield spots. He has also played first base, but the Marlins plan to test him out initially in right field.
The 18-year-old had a commitment to attend Rice University but instead is signing with Miami for $600,000.
The Marlins also have signed right-hander Sam Perez (fifth round), center fielder Corey Bird (seventh), center fielder Aaron Knapp (eighth), catcher Jarett Rindfleisch (ninth), left-hander Dylan Lee (10th), right-hander Chad Smith (11th), right-hander Mike King (12th), shortstop Ryan Nelson (15th), right-hander Dustin Beggs (16th), right-hander Brent Wheatley (17th), catcher David Gauntt (18th), left-hander Shane Sawczak (19th), shortstop Luis Pintor (21st), right-hander Alex Mateo (22nd), shortstop Jordan Gould (24th), second baseman Mike Garzillo (25th), right-hander Parker Bugg (27th), first baseman Colby Lusignan (28th), outfielder Walker Olis (29th), right-hander Chevis Hoover (32nd), first baseman Branden Berry (33rd), left-hander Trenton Hill (34th), second baseman Mathew Brooks (35th) and center fielder Zachary Daly (37th).
Miami also signed two undrafted free agents: catcher John Silviano from Lynn University, and right-hander Ty Provencher from Cal. State University-Long Beach.
Joe Frisaro has covered the Marlins for MLB.com since 2002. He writes a blog, called The Fish Pond. Follow him on Twitter @JoeFrisaro and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.