Early-onset hip osteoarthritis is commonly seen in people undergoing hip arthroscopy and is associated with increased pain, reduced ability to participate in physical activity, reduced quality of life and reduced range of motion and muscle strength. Despite this, the efficacy of non-surgical interventions such as exercise therapies remains unknown. The primary aim is to establish the feasibility of a phase III randomised controlled trial investigating a targeted physiotherapy intervention for people with early-onset hip osteoarthritis. The secondary aims are to determine the size of treatment effects of a physiotherapy intervention, targeted to improve hip joint range and hip-related symptoms in early-onset hip osteoarthritis following hip arthroscopy, compared to a health-education control.This protocol describes a randomised, assessor- and participant-blind, controlled clinical trial. We will include 20 participants who are (i) aged between 18 and 50 years; (ii) have undergone hip arthroscopy during the past six to 12 months; (iii) have early-onset hip osteoarthritis (defined as chondrolabral pathology) at the time of hip arthroscopy; and (iv) experience hip-related pain during activities. Primary outcome will be the feasibility of a phase III clinical trial. Secondary outcomes will be (i) perceived global change score; (ii) hip-related symptoms (measured using the Hip disability and Osteoarthritis Outcome Score (HOOS) pain subscale, activity subscale, and sport and recreation subscale); (iii) hip quality of life (measured using the HOOS quality of life subscale and International Hip Outcome tool; (iv) hip muscle strength and (v) hip range of motion. The physiotherapy intervention is semi-standardised, including joint and soft tissue mobilisation and stretching, hip and trunk muscle retraining and functional and activity-specific retraining and education. The control intervention encompasses individualised health education, with the same frequency and duration as the intervention. The trial primary end-point is the conclusion of the 12-week intervention, and follow-up measures will be collected at the 12-week post-baseline assessment.The findings of this study will provide guidance regarding the feasibility of a full-scale phase III randomised controlled trial, prior to its undertaking.The trial protocol was registered with the Australian Clinical Trials Registry (number: 12614000426684 ) on 17 April 2014.