Gossage was elected to the National Baseball Hall of Fame in 2008 and played in parts of seven seasons with the Yanks (1978-83, '89), winning a World Series with the team in 1978.
Martinez played in seven seasons with New York (1996-2001, '05) and helped to lead the team to four World Series victories during that time (1996, '98-2000). He will also be in attendance for Old-Timers' Day.
In addition to Gossage, the Old-Timers are headlined by Hall of Famers Yogi Berra, Whitey Ford, Rickey Henderson and Reggie Jackson, as well as Joe Torre, who will be inducted into the Hall of Fame in July. Current YES Network broadcasters David Cone, John Flaherty and Paul O'Neill will also participate.
Johnny Damon and Hideki Matsui, who won a World Series title with the Yankees in 2009, will make their Old-Timers' Day debuts, along with John "The Count" Montefusco, who helped the club produce three seasons of at least 90 wins from 1983-86.
Joining the Hall of Famers and former Yankees on the baselines will be the widows of six legendary Yanks -- Maggie Coleman, widow of Jerry Coleman; Arlene Howard, widow of Elston Howard; Helen Hunter, widow of Jim "Catfish" Hunter; Jill Martin, widow of Billy Martin; Diana Munson, widow of Thurman Munson; and Kay Murcer, widow of Bobby Murcer.
Ceremonies are scheduled to begin at 11:30 a.m. with the traditional Old-Timers' Game to follow, both of which will be aired on the YES Network. The Yankees will then host the Orioles at 2:05 p.m. Gates will open to ticket-holding guests at 10 a.m., and fans are encouraged to be in their seats by 11:15 a.m. for the festivities.
The plaques for Martinez and Gossage mark the first stage of this year's announced Monument Park additions. O'Neill's ceremony will take place on Aug. 9, and Torre will take his place in Monument Park on Aug. 23, with his uniform No. 6 set to be retired.
Bryan Hoch is a reporter for MLB.com. Follow him on Twitter @bryanhoch and read his MLBlog, Bombers Beat. This story was not subject to the approval of Major League Baseball or its clubs.