Free-agent cornerback Dre’ Bly signed a five-year contract Saturday with Detroit, helping the Lions fill a pressing need in the secondary.

A source within the league, who spoke on the condition of anonymity, said the deal was worth $24.5 million, including a signing bonus of just over $6 million.

The 25-year-old Bly leaves after four seasons with the St. Louis Rams, who picked him in the 1999 draft.

In 64 games with the Rams, Bly had 193 tackles and 14 interceptions.

He had 79 tackles (61 solo), two interceptions, two forced fumbles and a sack last season.

Bly also has filled in as a punt returner, running back 15 kicks for 209 yards and one touchdown in his pro career.

“We planned on being active and swift,” Detroit coach Steve Mariucci said. “In looking for the best corner available, certainly Dre’ Bly fits that description. He was our No. 1 targeted guy in free agency.”

St. Louis Rams player Dre' Bly (32) is congratulated by Chad Cota following a punt return for a touchdown in this file photo. Bly, a free agent, agreed to a deal Saturday with the Detroit Lions.

Detroit needed a solid cornerback after 12-year NFL veteran Todd Lyght retired.

The Lions hope to turn things around under Mariucci after going a combined 5-27 the past two seasons.

Bly said he had opportunities to visit other teams before making a decision, but Mariucci’s presence made him comfortable with turning away other suitors.

“He turned things around in San Francisco a few years ago when they were in the hole,” Bly said. “He got them to the playoffs and basically rebuilt the team. He didn’t have the ability to bring in free agents but still, he rebuilt that team and got them to the playoffs. I just looked at it as a perfect opportunity for me to help this team. Coach Mariucci — guys want to come in and play for him.”