BACKGROUND: Hallux rigidus, or osteoarthritis of the first metatarsophalangeal joint (MTPJ), causes pain and functional limitation. No randomized trials have compared surgery with the natural course of the disease. OBJECTIVE: To compare first MTPJ arthrodesis-a widely used surgical intervention-with watchful waiting in reducing walking-related pain in symptomatic hallux rigidus at 12 months after randomization. DESIGN: Single-center, parallel-group, randomized, controlled, superiority trial with 12-month follow-up. (ClinicalTrials.gov: NCT04590313). SETTING: Orthopedic department of a tertiary care hospital in Finland. PARTICIPANTS: Adults aged 40 years or older with radiographically confirmed (Coughlin-Shurnas grade I to III) hallux rigidus with symptoms over a year and a walking pain score of 4 or higher on a numerical rating scale (NRS) of 0 to 10 were eligible. Exclusion criteria included type 1 diabetes mellitus, rheumatoid arthritis, and hallux valgus angle greater than 15°. INTERVENTION: Participants were randomly assigned in a 1:1 ratio to surgery with first MTPJ arthrodesis using lag-screw and dorsal plating or to watchful waiting. MEASUREMENTS: The primary outcome was walking-related pain (NRS of 0 to 10) at 12 months. The prespecified minimal clinically important difference was 1.7 points. RESULTS: Between November 2021 and June 2024, 90 patients were randomly assigned (45 per group). The mean age was 58.1 years, and 89 participants completed the 12-month follow-up. At 12 months, the observed mean walking-related pain was 1.3 in the arthrodesis group and 5.7 in the watchful waiting group (adjusted mean difference, -5.0 points [95% CI, -6.1 to -3.9 points]), exceeding the prespecified minimal clinically important difference and favoring arthrodesis. LIMITATION: Single-center design. CONCLUSION: Among adults aged 40 years or older with painful hallux rigidus, first MTPJ arthrodesis provides a superior and clinically significant reduction in walking-related pain at 12 months compared with watchful waiting. PRIMARY FUNDING SOURCE: Suomen Lääketieteen Säätiö Foundation, Finland.