The start will be the two-time Cy Young award winner's first since September 2, 2010, having spent all of last season recovering from surgery to repair a torn anterior capsule in his throwing shoulder.
Santana has made five starts this spring, and has a 3.44 ERA with 13 strikeouts in 18 1/3 innings.
In the three seasons with the Mets prior to the shoulder surgery, Santana posted a 2.85 ERA and 7.4 K/9 over 600 innings pitched.
Manager Terry Collins told Martino that Santana's opening day pitch count will not exceed 95 pitches.
Johan Santana officially named Opening Day starter for NY Mets | NY Daily News
The Mets on Sunday morning made their starting rotation official, naming Johan Santana their Opening Day starter. Santana will be followed by R.A. Dickey, Jon Niese, Mike Pelfrey and Dillon Gee.