Wuornos, 46, was sentenced to death six times for killing middle-aged men when she worked as a prostitute along the highways of central Florida in 1989 and 1990.
"I'm glad that it's over," said Terry Griffith, whose father, Dick Humphries, was one of Wuornos' victims. She witnessed the execution. "In my opinion, it was a very easy death, it was a little bit too easy."
One of the few female serial killers in the United States, she fired her attorneys and dropped her appeals despite lingering questions over her sanity. Her case has spawned two movies, an opera and several books.
"I'd just like to say I'm sailing with the Rock and I'll be back like Independence Day with Jesus, June 6, like the movie, big mothership and all. I'll be back," Wuornos said from the execution chamber. The Rock is a Biblical reference to Jesus.
Fort Lauderdale lawyer Raag Singhal, wrote a letter to the state Supreme Court last month expressing "grave doubts" about Wuornos' mental condition, said that confirmed what he believed.
"I believe that she's mentally ill," he told reporters. "I don't think we should be executing somebody simply because they're a volunteer."
For years, Wuornos claimed she shot the men out of self-defense while being raped and sodomized. At a hearing last year, reports CBS News Correspondent Michael Hibblen, she dropped her appeals and admitted to a judge that she killed the men while working as a hitchhiking prostitute.
"As soon as they picked me up and we'd park out in the woods, I whipped out the gun and shot 'em," she said. "That's cold. I do deserve to die. So I'm doing the correct thing. I'm doing the right thing."
"There's no point in moving any further with my life. I've just gotta go. I'd never change," she said. "There's no chance...in keeping me alive or anything because I'd kill again. I have hate crawling through my system."
Gov. Jeb Bush issued a stay and ordered a mental exam, but lifted the stay last week after three psychiatrists who interviewed her concluded that she understood she would die and why she was being executed.
State Attorney John Tanner, who watched psychiatrists interview her for 30 minutes last week, said she was cognizant and lucid. "She knew exactly what she was doing," Tanner said.
Prison spokesman Sterling Ivey said for the most part Wuornos had been in good spirits over the last week.
"At times she's been agitated, but for only brief periods," he said. "No reason for the agitation, but she's been remarkably in a very good mood."
With Wuornos' execution, she joins Judy Buenoano as the only women Florida has killed since resuming the death penalty in 1976. Fifty-one men have been executed by Florida during that span.
Across the United States, state and federal authorities have put 804 inmates to death since the U.S. Supreme Court lifted the moratorium on the death penalty in 1976.
The state Supreme Court on Tuesday rejected two efforts to stop the execution: a private attorney in Tampa who expressed "serious concerns" about Wuornos' competency, and a request by an Ohio group that wanted to file an appeal on Wuornos' behalf.
Billy Nolas, who represented Wuornos in her 1992 trial in Daytona Beach, said she suffered from borderline personality disorder as a result of neglect and sexual abuse as a child.
"She is the most disturbed individual I have represented," said Nolas.