The Avalanche made a big move to shape its roster Tuesday when it re-signed restricted free agent Erik Johnson to the longest contract of his career. The big defenseman signed a four-year, $15 million contract that will pay him $3.25 million this season and $4.25 million in 2015-16.

Johnson, 24, previously signed three- and two-year deals with the St. Louis Blues, who selected him with the first pick of the 2006 draft.The Avs acquired him late in the 2010-11 season.

“I’ve wanted to be in Colorado the whole time, and the four-year deal is so good for me and my family. I’m excited to be a part of the Avalanche for the next four years,” Johnson said in a phone interview. “Right from the get-go in negotiations, we targeted the four-year deal. I’m very excited, very appreciative and very grateful for this opportunity from the Avalanche.”

In his first full season with the Avs, Johnson contributed four goals and 26 points in 73 games, leading the team’s defensemen in scoring.

“Since Erik’s arrival in Colorado, he has provided stability, size and an offensive presence to our blue line,” Avalanche general manager Greg Sherman said in a news release. “At only 24 years of age, we believe that Erik will continue to grow his game, and we are thrilled to have him under contract.”

Johnson’s signing increases the Avs’ logjam at the blue line, where seven veterans and three prized prospects are under contract. The Avs signed unrestricted free agents Matt Hunwick and Shane O’Brien, plus restricted free agent Ryan Wilson, before the free-agent period began Sunday. They signed free agent Greg Zanon, who played for Minnesota and Boston last season. Ryan O’Byrne and Jan Hejda already were locked in, as were youngsters Stefan Elliott, Tyson Barrie and 2011 first-round draft pick Duncan Siemens.

Defenseman Cameron Gaunce, 22, who led the Avs’ American Hockey League team with a plus-17 rating last season, also is under contract as a third-year pro.

“Every team I’ve been on, it seems we’ve been decimated by injuries on defensemen, and, as the saying goes, you can never have too many defensemen,” Johnson said. “So I think what management has done is excellent. When you have depth like that, it creates internal competition amongst all the defensemen, and that brings up the level of play.”

The Avs have more than 25 players with significant NHL experience under contract. The only remaining big-name restricted free agents are forwards Ryan O’Reilly and Jamie McGinn. Newly signed free-agent forwards P.A. Parenteau and John Mitchell are expected to replace unrestricted free agents Peter Mueller and Kevin Porter.

Mike Chambers: 303-954-1357 or mchambers@denverpost.com