Background/Objectives: Various psychological and sociodemographic factors are strongly associated with shopping addiction in different populations. To date, the relationships between these variables have not been fully clarified. European data indicate a rise in shopping addiction among adults over the past two decades, but population-based epidemiological studies in Central and Eastern Europe, including Croatia, remain scarce. This study was conducted to examine the prevalence of shopping addiction and its related factors in Croatian adults. Methods: A cross-sectional online survey was conducted, with data collected via Google Forms from February to April 2024. An anonymous questionnaire covering sociodemographic data, the Bergen Shopping Addiction Scale (BSAS), and the Rosenberg Self-Esteem Scale (RSES) was self-administered by participants recruited using snowball sampling of Croatian adults. Results: The study included 715 participants from all Croatian regions. In the present sample, 14.3% of participants met the BSAS ≥ 12 cutoff, indicating probable and problematic shopping addiction. The BSAS score was significantly higher among females (p = 0.008), high school and university students (p = 0.048), and young adults aged 18–25 years (p = 0.042). Most participants reported average self-esteem (68.0%), while 31.2% and 0.8% had low and high self-esteem, respectively. BSAS scores correlated positively with RSES scores (ρ = 0.225; p < 0.001), while age was negatively correlated with both BSAS (ρ = −0.147; p < 0.001) and RSES (ρ = −0.356; p < 0.001) scores. After controlling for age and sex, the correlation between BSAS and RSES scores remained significant: partial rho = 0.103 and p = 0.006. Conclusions: Shopping addiction was prevalent in the studied population and was associated with specific sociodemographic characteristics and self-esteem levels, highlighting the need for targeted preventive strategies and further research into its underlying mechanisms.