Jalin Marshall is back.

The Jets activated the second-year receiver off the reserve/suspension list and to the 53-man roster on Monday, coach Todd Bowles said via conference call. To make room, they released veteran cornerback Marcus Williams.

Marshall, 22, signed with the Jets as an undrafted free agent last year. He made the team after an impressive training camp, and saw spot duty throughout the year on offense and special teams.

This offseason, the NFL suspended Marshall four games after he tested positive for PEDs. His suspension ended last week, but the Jets received a one-week exemption to decide if they wanted to activate, or cut, him. Marshall practiced with the Jets last week.

"I'm just ready to be back around football, the guys, the team," Marshall told NJ Advance Media last week. "Those are the things you lose during those four weeks. Those are the things that make you who that are. To gain it all back? I'm excited. I'm so excited to be back here. I can't wait."

Marshall went home to Cincinnati, Ohio to serve his suspension. He worked out six days a week, and said he's in the best shape of his life.

Marshall primarily plays slot receiver, but has experience returning kicks and punts, too. The Jets current slot receiver is veteran Jeremy Kerley, who also returns punts. Kerley has 17 catches for 132 yards this year. He's averaging 7.7 yards on seven punt returns.

"My point of emphasis was always to be ready," Marshall said. "I don't know what's going to happen. I might be here. I might not. Wherever I end up, I want to be ready. Hopefully, it's here with the Jets. I'm confident it will be. I'll be ready. That's my main focus."

The decision to release Williams for Marshall is a bit of a surprise. The Jets gave the cornerback a second-round tender this offseason, which awarded him a one-year, $2.746 million contract. The deal was not guaranteed, though.

After getting waived by the Texans in 2014, Williams, 26, joined the Jets. A year later, he led the team in interceptions (6) as a situational cornerback and safety. Last year, he had two interceptions in 13 games.

Williams struggled in training camp this summer and fell on the depth chart. He didn't play a single defensive snap the first four games. With Juston Burris and Darryl Roberts inactive in Sunday's victory over the Browns, Williams played, but struggled.

Bowles said the decision to release Williams came down to numbers.

"The other guys were playing better," Bowles said. "Roberts and Burris had great camps. You fall behind the eight ball, then it's a numbers thing.

"I think Marcus will land and play somewhere. We just have guys that are playing better at the time."

Connor Hughes may be reached at chughes@njadvancemedia.com. Follow him on Twitter @Connor_J_Hughes. Find NJ.com Jets on Facebook.