The abduction was caught on a widely broadcast car-wash surveillance video, leading to the arrest of Smith after people who recognized him on the tape identified him.
Circuit Judge Andrew D. Owens also sentenced Smith to two terms of life in prison for kidnapping and raping Brucia. He sentenced Smith to five years in prison, with credit for time served, for a violation of his probation.
Owens called the murder "cold and calculated and premeditated." Smith "held Carlie's life in his hands for not seconds, but minutes" as he slowly strangled her, Owens told the court Wednesday.
"At that time, the defendant had no idea his actions were being filmed by video cameras," and his nametag read "Joe," Owens said, reasoning that Smith did not intend to kill Brucia. It was "initially sexually motivated," Owens said.
"Carlie endured unspeakable trauma," Owens said. "The image of the defendant taking her arm and leading her away will forever be etched" in our minds."
Smith, 39, showed no emotion as the judge read his sentence.
The jury that convicted Smith in November had recommended by a vote of 10-2 that he be executed.
CBS News RAW video of Smith's reaction to his death sentence. Watch a report of Smith's sentencing hearing, including the car-wash surveillance video.
Last month, Smith had tearfully apologized during a hearing, saying: "I take responsibility of my crimes. I don't understand how this could have happened. ... Every day I think about what I did and beg God for forgiveness."
On Wednesday, Owens said Smith's actions were deliberate and planned. He called Smith's crimes especially cruel, considering that Carlie never had a chance to fight back or escape.
Carlie's aunt says while justice has been served, the family has little reason to celebrate, CBS News' Christopher King reports.
"Am I happy with the verdict?," Laurie Brucia said. "Happy would be to have Carlie here."