Mijailovic, 25, had denied murder, insisting he carried out the attack because of "voices in his head," which was disputed by psychiatrists, the BBC reported.
Lindh died of her injuries in a hospital Sept. 11, one day after the attack in a department store.
"He used a life-threatening weapon. He held the knife with both hands when he delivered the blows ... the force was powerful," the court said in a statement. "The location and the size of the stab wounds indicates that the intention was to kill."
His defense team had sought a manslaughter verdict and psychiatric care for him, but the jury ruled he must be held at least 10 years before his sentence can be reviewed.