"There was never really any doubt in my mind that we were going to get everything done on time," Keller said. "I'm just happy that everything's done and to officially be a New York Jet -- just happy that all that stuff's done now and we can actually get down to the real football business and get the pads on."
Keller was the 30th selection in the first round and his signing leaves the Jets with one unsigned rookie, linebacker/defensive end Vernon Gholston, the sixth pick in the draft.
Keller caught 142 passes for 1,882 yards and 16 touchdowns for Purdue.
"I feel pretty confident with the offense right now. I've been doing a lot of studying and getting everything down," Keller said. "As far as expectations for the season, I haven't really set any true expectations for myself. For right now, I just want to get the offense down as good as I can and I want to go out there and give the Jets everything I've got every chance I'm out there."
The Jets have had some of their rookies in for orientation this week. Their camp begins Wednesday.
The Associated Press contributed to this report.