Hayes, 29, also received a 15-year sentence for attempted manslaughter in the shooting of Racquel Smith, wife of the former defensive end.
Prosecutors argued that Hayes should serve 60 years for the two convictions, and Racquel Smith was disappointed that Criminal District Judge Camille Buras went with a combined total of 40 years.
"My family and I are extremely disappointed with today's sentencing and the leniency showed by Judge Buras for the defendant," Smith said in a statement. "While we know nothing will ever bring Will back, we were hopeful that Judge Buras would have issued a stronger sentence to more justly reflect both the nature of the crimes and the tremendous loss and pain that my family has suffered as a result of Mr. Hayes' violent actions on the night of April 9, 2016," she said.
"This ordeal has been a nightmare for me and my family. There are no winners here today. Today's sentencing does not bring back Will and leaves another child to grow up without a father. I pray for the other families of New Orleans that are dealing with the same tragedy that comes with the loss of life at the hands of senseless violence.
"Will loved this city and we must do better together to enact serious change so that Will's unnecessary murder is not in vain."
The shooting of Will Smith occurred after a minor traffic incident on April 9, 2016, on the streets of New Orleans.
According to the police report, Hayes' vehicle hit Smith's SUV from behind and an argument ensued. Smith, 34, was struck by eight bullets, including seven in the back, and died at the scene. His wife was shot twice in a leg.
Hayes was convicted of the crimes in December.
Will Smith played nine seasons with the Saints (2004-12) and recorded 67.5 career sacks.