This study was conducted to evaluate the short-term efficacy of a web-based behavioral weight loss intervention among 101 primary care patients with obesity and hypertension. The intervention, named “Step Up, Trim Down”, consisted of access to a comprehensive weight loss website for 12 weeks, along with four (two in person and two telephonic) counselling sessions with a health coach. This web-based behavioral weight loss intervention generated 3.05 kg greater weight loss among obese, hypertensive patients than usual care alone. The intervention approach was of moderate intensity and gave a walking recommendation combined with simple behavior modifications. This study adds support to the promotion of internet as a plateform to deliver effective weight loss interventions and to reach a wide population.