The study aimed to investigate the effectiveness of teaching using the Problem-Solving-Based model on the algebraic thinking and the attitude towards mathematics among eighth-grade female students. The study used a quasi-experimental approach and had a total of 69 participants from the Governorate of Muscat in the Sultanate of Oman, divided into an experimental group 34 students and a control group 35 students. The study constructed teaching materials based on the problem-solving- based model and used two reliable tools to gather data: The Algebraic Thinking test made up of 14 items and the Attitude Towards Mathematics Scale consisting of 24 items. The results of the data analysis related to the effectiveness of the teaching program showed that there were statistically significant differences at the significance level (α ≤ 0.05). The mean scores of the experimental group were higher than the mean scores of the control group regarding the total algebraic thinking test and all its related skills and the total mean scores of the attitudes towards mathematics scale and two of its dimensions, particularly: realizing the value of learning mathematics and enjoying learning mathematics. Considering the previous findings, the research proposes several recommendations. The foremost recommendation is to utilize the teaching guide that was developed by the researcher in this study. Additionally, teachers should be introduced to algebraic thinking skills and techniques to advance them. It is also crucial to consider students' attitudes towards mathematics, as it positively impacts academic achievement and enhances their motivation to learn. The study suggests conducting further research to explore the efficacy of problem-based teaching models on various research variables.