Listeria monocytogenes is a well-known foodborne pathogenic bacterium responsible for severe diseases in humans and animals. Additionally, the increase in antibiotic resistance rates of L. monocytogenes strains after exposure to preservatives, antibiotics, and stress conditions has become another major public health issue. This study focuses on the serological identification of 11 L. monocytogenes isolates from milk (n=1), whey (n=2), and ice creams (n=8) and the investigation of the pathogen's antibiotic resistance. The serological typing of the strains involved using multiplex PCR for each of the strains, with 63.6% of them belonging to serogroup IVb, 27.3% to serogroup IIb, and 9.1% to serogroup IIa. It was noteworthy that all the strains of serogroup IVb, which includes serotype 4b, most commonly responsible for listeriosis outbreaks in humans, were isolated from one of the three companies from which the samples were taken, and concerned the ice cream production line. Regarding the antibiotic resistance of the strains, antibiograms of the pathogen isolations were assessed against a group of seven selected antibiotics (erythromycin, tetracycline, penicillin, trimethoprim–sulfamethoxazole, ampicillin, ciprofloxacin, and meropenem) which showed that six strains exhibited resistance to at least one of the examined antibiotics, while no strain exhibited resistance to ampicillin and meropenem, with the former being the drug of choice for the treatment of listeriosis. Two strains of serogroups IIb and IVb exhibited resistance to four and three antibiotics, respectively. The findings of this study are useful and could be utilized for epidemiological research on L. monocytogenes in the food-processing environment, revealing potential contamination scenarios, resistance to sanitization, and the persistence of the pathogen in the food-processing environment, as well as acquired microbial resistance along the food production chain.