Turner was informed of the decision by manager Terry Collins on Wednesday before the team left for a game against the St. Louis Cardinals in Jupiter, Fla. Turner batted .231 (9 for 39) this spring with two doubles and five RBI.
Emaus is batting .235 with a .366 on-base percentage. Emaus is a Rule 5 selection, which would require the Mets to offer him back to Toronto if he doesn't remain on the major- league roster this season.
Luis Castillo was let go by the Mets on Friday despite being owed $6 million in the final year of a four-year deal. Daniel Murphy and Luis Hernandez also are in competition for the starting job at second base.
"I'm sure Brad's feeling pretty good about himself right now," Turner said. "Anytime someone gets taken out of the picture, obviously that's a little more opportunity for you."