The rise of antimicrobial resistance, driven largely by the inappropriate use of antibiotics, presents a significant global health challenge. Healthcare professionals (HCPs) self-medication practice (SMP) with antibiotics is a concerning practice. The role of knowledge, and attitudes, in shaping SMP has not been explored, in the context of Ethiopia. This study aims to investigate the patterns of antibiotic use, knowledge, attitudes, and associated the factors with SMP among healthcare professionals in tertiary hospitals in Bahir Dar, North West Ethiopia. A cross-sectional study was conducted from September 2023 to February 2024 in two tertiary hospitals in Bahir Dar, Ethiopia. The study included 410 healthcare professionals selected using proportional allocation and convenience sampling. A structured, self-administered questionnaire was used to assess participants' demographics, knowledge, attitudes, and practices regarding antibiotic use. Knowledge was assessed through scoring, and attitudes were evaluated using a Likert scale. Data were analyzed using SPSS version 27.0, employing bivariate and multivariate logistic regression analyses to identify factors associated with SMA. Knowledge assessment revealed that 58.5% had good knowledge. In terms of job categories, nurses comprised the largest group (48.8%). A majority (60.2%) had 1-5 years of experience. 57.8% of participants exhibited a poor attitude to SMP. Respiratory infections (20.61%) were the most common health condition reported, followed by gastrointestinal infections (15.43%). The most frequently used antibiotics were amoxicillin (35%), augmentin (25%), and azithromycin (25%). Key factors influencing SMA included ease of access to antibiotics (36%), cost-effectiveness (23%), and knowledge/expertise (22%). Time constraints, perceived severity of conditions, and past self-medication experiences were also significant factors. While 83.8% considered self-medication to be safe, 75% recognized the potential adverse effects of medications. The multivariate analysis revealed that being a physician (AOR = 23.39) or a pharmacist (AOR = 7.79) was strongly associated with self-medication. Degree holders, MSc holders, and specialized physicians were also more likely to self-medicate. A poor attitude was a significant determinant, with healthcare professionals displaying poor attitudes being almost twice as likely to self-medicate (AOR = 1.91). The findings highlight the prevalent practice of self-medication with antibiotics among healthcare professionals in Ethiopia, influenced by factors such as knowledge, access to antibiotics, and professional attitudes. The study highlights the urgent need for targeted interventions to enhance healthcare professionals' knowledge and attitudes regarding responsible antibiotic use while addressing their own practices of self-medication.