Background/Objectives: Recently, epigenetic mechanisms have been recognized as crucial in atopic dermatitis development. The emphasis of this research was on expanding existing knowledge about the epigenetic aspects of atopic dermatitis, as well as identifying new molecules that could serve as disease biomarkers. Methods: The research was conducted as a cross-sectional study examining two groups: the group with atopic dermatitis (50 patients) and the control group (50 healthy adults). The serum levels of total immunoglobulin E (IgE) and eosinophil count (Eos%) were performed in routine laboratory analyses, and the detection of microRNAs from peripheral blood was performed using RT-PCR. Results: Analysis of selected miRNA expressions in patients with atopic dermatitis and controls revealed that only the expression and the relative expression of miRNA-146a were statistically significantly higher in patients with atopic dermatitis than in the control group (p = 0.042 and p = 0.021, respectively). There was a weak positive correlation between miRNA-146a expression and the eosinophilia/IgE level (r = 0.22 and r = 0.25, respectively). MiRNA-21, miRNA-29b, miRNA-143 and miRNA-223 were significantly upregulated in patients with higher SCORAD (p < 0.001, p < 0.001, p < 0.001 and p = 0.015, respectively). ROC curve analysis revealed the specificity of miRNA-146a as 82% and the sensitivity as 62%. The area under the ROC curve (AUC) was 0.7, indicating its diagnostic potential. Conclusions: Our findings imply that miRNA-146a might serve as a biomarker of atopic dermatitis, suggesting its relevance in the development of the disease, while miRNA-21, miRNA-29b, miRNA-143 and miRNA-223 may have an impact on disease progression. Our findings provide a preliminary basis that should precede validation through larger, multicentric studies and use in diagnostics, targeted personalized treatments and monitoring of treatment efficacy in atopic dermatitis.