The incident took place on July 14 at a Tasty Dot restaurant in the city of Rostov, according to The Sun.
The act was recorded on video and later circulated widely on social media.
The worker, identified as Nikita, was seen preparing two burgers when he glanced around to ensure no one was watching. He then leaned in, spit on one of the burger patties, and used a spoon to spread it across the surface, News.com.au reported.
He placed a slice of cheese on top to conceal his actions before boxing up the meal and sending it through the delivery window.
The customer, who had earlier argued with Nikita when placing the order, became suspicious of the employee’s attitude and secretly filmed the food preparation process.
The video quickly went viral, sparking widespread condemnation across Russian social media.
Many users criticized Nikita’s behavior and voiced concerns over hygiene and food safety at Tasty Dot, a relatively new fast food chain.
In response to the backlash, Nikita claimed he was provoked: "They were shouting, swearing, and demanding that I hurry up. Then they threatened to get out of the car and beat me."
Tasty Dot issued a statement saying it had terminated Nikita’s employment, stating that his actions were "completely inconsistent with the company’s core values."