Background and Objectives: Frontal recess cells (FRCs) are key anatomical variants influencing frontal sinus drainage and disease. The International Frontal Sinus Anatomy Classification (IFAC) provides a standardized system for their identification. The baseline data on FRC prevalence and its association with sinusitis in Middle Eastern populations remain limited. This study aimed to assess the prevalence, laterality, and clinical relevance of FRCs in an adult Omani population using IFAC criteria. Materials and Methods: Computed tomography (CT) scans of 488 sides from 244 adult Omani patients were retrospectively reviewed to identify the FRCs according to IFAC. A total of 123 patients were found to have sinusitis: bilateral in 37 patients, right-sided in 38 patients, and left-sided in 48 patients. The prevalence of FRCs, along with their laterality and gender differences, was evaluated. Furthermore, the association between FRCs and sinusitis was analyzed using a chi-square test, followed by multivariable logistic regression analysis. Results: Among overall subjects (244 patients; 488 sides), agger nasi cells (79.5%, n = 388) and supra bulla cells (64.1%, n = 313) were the most prevalent cell types, whereas frontal septal cells (8.8%, n = 43) were the least common. Among study subjects (n = 244), laterality differences in FRC frequency were observed in the frontal septal cells, with a higher frequency of cells on the right side (p = 0.01), while no significant differences were found in other cell types. The presence of supra agger frontal cells (OR = 1.544, 95% CI: 1.02–2.23, p = 0.03) was positively correlated with sinusitis, while the presence of supra bulla cells was inversely associated with frontal sinusitis (OR = 0.61, 95% CI: 0.41–0.93, p = 0.01). The presence of FRC type was not significantly associated with the degree of sinusitis (p > 0.05). Significant gender differences were observed in supra orbital ethmoid cells (p = 0.01), with a male predominance. Conclusions: This study provides baseline data on the prevalence of FRCs in the Omani population. The presence of supra agger frontal cells appears to be associated with frontal sinusitis. No statistically significant gender- or laterality-associated differences were observed in most FRC types. Preoperative identification of supra agger frontal cells may facilitate effective surgical planning, particularly for endoscopic sinus surgery.