Walker, a 21-year-old rookie right-hander expected to challenge for a rotation berth, was just named the No. 6 overall prospect in baseball by MLB.com.
Also scheduled to take part in the 16th annual FanFest are new outfielders/first basemen Corey Hart and Logan Morrison, as well as catcher Mike Zunino, outfielder Michael Saunders, shortstop Brad Miller and pitchers Tom Wilhelmsen and James Paxton.
Young prospects Stefen Romero, Chris Taylor, Carson Smith and D.J. Peterson also will be making appearances, as will new manager Lloyd McClendon and general manager Jack Zduriencik.
Hart is only scheduled to be available on Sunday. Former catcher Dan Wilson is on the slate for Saturday. A full schedule of appearances and autograph sessions each day is available on the Mariners FanFest page.
The event goes from 11 a.m. to 4 p.m. PT on both days. Tickets are $10 for adults, with children 14 and under admitted for free. Tickets are on sale now at mariners.com and at Mariners Team Stores, or are available at the Safeco Field ticket windows during the event.
Parking will be available at the Safeco Field garage for $5 in advance, or $10 at the door.
FanFest activities include autograph availability with the various players, and dugout dialogue sessions where fans can ask questions of players, coaches and front-office personnel. Fans can also run the bases, tour the Mariners' clubhouse, ride two different zip lines over the Safeco Field playing surface, throw a pitch in the bullpen, hit a simulated Felix Hernandez fastball in a batting cage, play games in the Kids Fun Zone and swing game-used bats or try on players' gloves in a "Tools of the Trade" exhibit.
The club is also making tickets for the April 8 home opener against the Angels available in a special presale from 10 a.m. on Friday through 11:59 p.m. on Sunday, either online at mariners.com/tickets, at the Safeco Field box office, or at Mariners Team Stores.
If they're not sold out, Opening Night tickets will then be available again starting March 8, when all Mariners 2014 single-game tickets will go on sale to the public.