The 2023 3. deild karla (English: Men's Third Division) was the 69th season of fourth-tier Icelandic football. The season began on 4 May 2023 and finished on 16 September 2023.
Twelve teams contested the league. The title winners (Reynir) and runners-up (Hvöt Blönduós) were promoted to the 2024 2. deild karla. The bottom two teams (KFS and Ymir) were relegated to the 2024 4. deild karla.
Each team played each other twice (22 matches each), once at home and once away.