Yelich and Fernandez are Miami's top two prospects; each is expected to open the regular season at Double-A Jacksonville.
Yelich was the team's first-round pick in 2010; Fernandez went in the first round in 2011.
Thirty-one non-roster invitees will be in Marlins camp, and 71 players overall.
Along with Yelich and Fernandez, the Marlins have invited homegrown picks Adam Conley, Andrew Heaney and Jacob Realmuto to Spring Training. Jake Marisnick, an outfield prospect acquired from the Blue Jays, also will be in camp.
Miami has also announced the signings of John Maine, Chad Qualls, Kevin Slowey, Matt Downs, Nick Green and Austin Kearns to Minor League deals with Spring Training invites.
Joe Frisaro is a reporter for MLB.com. He writes a blog, called The Fish Pond. Follow him on Twitter @JoeFrisaro. This story was not subject to the approval of Major League Baseball or its clubs.