With the Oct. 31 deadline looming, the Blazers needed to strike a deal with Aldridge or he would have become a restricted free agent next summer.
Aldridge signed a deal that with incentives could pay him nearly $70 million.
"Whether it was during the summer or now, I feel blessed," he said.
Aldridge joked that he called his mom to tell her about the deal and she didn't believe him. Georgia Aldridge was on her way to
Portland on Friday to personally thank general manager Kevin Pritchard and the Blazers, Aldridge said
"From day one I've always felt loved here -- so I'm glad that it's done," Aldridge said.
The second overall pick in the 2006 draft out of Texas, Aldridge was acquired by the Blazers in a draft-day trade from the Chicago Bulls. Last season, he averaged 18.1 points and 7.5 rebounds.
For his career, Aldridge has averaged 15.4 points and 6.8 rebounds. He has started in 157 games.
The 6-foot-11 Dallas native was key to a young Blazers team that won 54 games last season and went to the playoffs for the first time since 2003. Portland fell in six games to the Houston Rockets in the first round.
Aldridge started all six playoff games, averaging 19.5 points and 7.5 rebounds.
"LaMarcus is the epitome of what we're about. He's a hardworking, committed and unselfish young man who plays the right way," general manager Kevin Pritchard said.
The Blazers needed to strike a deal with Aldridge by Oct. 31 to prevent him from becoming a restricted free agent next summer.
His signing of an extension capped a busy day for the Blazers. Earlier, they waived forward Ime Udoka and center Jarron Collins, bringing their roster to 15 players for the start of the season next week.
Both Udoka and Collins were vying for the 15th spot, which went to draft pick Patty Mills, who is out with a broken foot.
Udoka has played five seasons in the NBA, including a previous stint in Portland. He averaged 6.8 points, 3.4 rebounds and 18.8 minutes in five preseason games.
Collins, who played eight years with the Utah Jazz, played in four preseason games with an average of 3.5 points, two rebounds and 14 minutes.
Mills fractured the fifth metatarsal in his right foot during practice in the offseason. It is not clear when he will return.
After starring for Australia in the Beijing Olympics and for Saint Mary's in college, Mills was selected by the Blazers with the 55th overall pick in the NBA draft.
The 6-foot, 175-pound Mills averaged career highs of 18.7 points, 4.0 assists, 2.6 rebounds and 2.5 steals during his sophomore season with the Gaels before deciding to turn pro.
Information from The Associated Press was used in this report.