The show's producers said on Twitter that the former child star -- commended by a judge Wednesday as "back on track" after repeated run-ins with the law -- would host the program on March 3, with Jack White as the musical guest.
Lohan -- who made headlines when she posed nude for Playboy last month, reportedly earning nearly $1 million for the photo spread -- was quick to express her thanks, writing on Twitter: "SNL, I love NBC."
But others in the Twittersphere were not so thrilled.
"Oh dear, what a hot mess that will be #SNL," wrote one user with the handle Harry Potter. Another, named Jio de Leon, added: "I am expecting this to be a train wreck, just like her life."
Another user, Laura Black, urged her followers to call SNL producers and the NBC television network to demand that they pull Lohan from the line-up.
Lohan -- the star of hit Disney movies "The Parent Trap" and "Freaky Friday" as well as "Mean Girls" -- is well known for her hard partying and has faced a series of legal tangles over the years.
In January California judge Stephanie Sautner said the actress, 25, was doing well in complying with the terms of her probation, meaning it could be over at the end of March.
And on Wednesday the same judge gave gave Lohan another glowing report, as she appeared in court in Los Angeles for her latest probation review.
"Miss Lohan, you're in the home stretch," she said. "The probation officer is pleased with your progress. You seem to be getting your life back on track and that's what we all hoped for.
"It was never our goal to just put people in jail, we like to see ... change, and I think we've all seen that," Sautner added.
Lohan has one more court hearing scheduled for March 29, before which she must complete 14 more days of community service at the county morgue and five more therapy sessions.
The actress was sentenced to 35 days of house detention last May as part of a plea bargain over the alleged theft of a $2,500 necklace from a jewelry shop near her home in Venice Beach.
In November, Lohan spent five hours in prison after being sentenced to a 30-day stretch for breaching probation on previous offenses including a 2007 drug and drunk driving misdemeanor.
Lohan also recently landed a starring role in a made-for-television film about Elizabeth Taylor, US media have reported.