New Orleans also signed second-round safety Marcus Williams out of Utah, third-round running back running back Alvin Kamara out of Tennessee, third-round linebacker Alex Anzalone out of Florida, third-round defensive end Trey Hendrickson out of Florida Atlantic and sixth-round defensive end Al-Quadin Muhammad out of Miami.
Lattimore, who was the 11th overall pick, recorded 46 tackles and four interceptions in two seasons at Ohio State. He is expected to start immediately at cornerback opposite Delvin Breaux and P.J. Williams.
The Saints' second first-round selection, Wisconsin offensive tackle Ryan Ramczyk, is the lone pick yet to be signed from the late April draft.
Ramczyk was chosen 32nd overall with the pick New Orleans received from the New England Patriots in the Brandin Cooks trade. Ramczyk has been limited during OTA practices as he recovers from hip surgery.