Purpose: The purpose of this finite element analysis (FEA) was to evaluate and compare stresses generated in bone, with carbon fiber-reinforced polyetheretherketone (CFR-PEEK) and titanium ball and locator attachments, in CFR-PEEK and titanium implant-supported mandibular overdenture. Materials and methods: In this FEA study, two mandibular models were formed using three-dimensional (3D) scans. One model represented a completely edentulous mandible with two implants placed in the interforaminal region and loaded with an overdenture using ball attachment systems. Similarly, the second model consisted of locator attachment systems. Each model was divided into four subgroups according to the material (CFR-PEEK and titanium) used for the implant and attachment system. A 100 N vertical load and a 100 N oblique load (20° oblique) were applied in the canine region on the overdenture. The von Mises stresses and maximum and minimum principal stresses were analyzed using the analysis of systems software. Results: In ball attachment groups, a combination of CFR-PEEK implant and attachment showed the least stresses in bone (1.977 and 1.090 GPa) and implants (0.028 and 0.005 GPa) under vertical and oblique loading, respectively. Similarly, in locator attachment groups, combination of CFR-PEEK implant and attachment showed least stresses in bone (0.475 and 0.306 GPa) and implants (0.183 and 0.105 GPa) under vertical and oblique loading, respectively. When ball and locator attachment were compared, the minimum stresses in bone and implant were seen in the CFR-PEEK implant and CFR-PEEK locator attachment system. Conclusion: The use of locator attachment systems is better than the ball attachment system, as it increases the durability of the overdenture by decreasing the stresses in bone and implant systems. CFR-PEEK implant along with CFR-PEEK attachments can be used in overdenture cases, as it decreases the stresses in surrounding bone compared to titanium implant and attachments.