Employing Self-Determination Theory (Deci & Ryan, 1985) as a theoretical framework, this study examined psychological need satisfaction and motivational regulations as predictors of psychological and behavioural outcomes in exercise referral (ER). ER patients (N = 293; mean age 54.49) completed the measures of motivational regulations, psychological need satisfaction, health-related quality of life, life satisfaction, anxiety, depression and physical activity at entry, exit and 6 months following the end of a supervised exercise programme. Change in (Δ) intrinsic motivation during the scheme significantly predicted adherence and Δ habitual physical activity. Δ psychological need satisfaction from entry to exit significantly predicted Δ habitual physical activity from exit to 6-month follow-up. Δ psychological need satisfaction significantly predicted Δ motivational regulation and Δ psychological outcomes. Contrary to expectations, Δ self-determined regulation did not significantly predict Δ psychological outcomes during the structured part of the scheme, however, it did significantly predict Δ in psychological outcomes from exit to 6-month follow-up. These findings expand on cross-sectional research to demonstrate that psychological need satisfaction during supervised ER longitudinally predicts motivational regulation and psychological outcomes up to 6 months after a structured programme.