The study investigated the effect of Problem-based learning (PBL) on senior secondary school students' achievements in Further Mathematics (FM) in Nigeria within the blueprint of pretest-post-test non-equivalent control group quasi-experimental design. Intact classes were used and in all, 96 students participated in the study (42 in the experimental group taught with the PBL and 54 in the control group taught using the Traditional Method (TM)). One research instrument manipulated at two levels namely: Teacher-Made Test (TMT) and Researcher-Designed Test (RDT), was developed and used for the study and data collected were analysed using the descriptive statistics of mean and standard deviation which served as precursor to testing the two hypotheses for the study using an independent samples t-test. Results showed that there were statistically significant differences in the mean post-test achievement scores on TMT and mean post-test achievement scores on RDT between students exposed to the PBL and those exposed to the TM, all in favour of the PBL group. Based on the results, the study recommended that the PBL should be adopted as alternative instructional strategy to the TM in enhancing meaningful learning in Further Mathematics classrooms and efforts should be made to integrate the philosophy of PBL into the pre-service teachers' curriculum at the teacher-preparation institutions in Nigeria.