Background: Professional caregivers are important in the daily support of lifestyle change for adults with mild intellectual disabilities; however, little is known about which behaviour change techniques (BCTs) are actually used. This study aims to gain insight in their use for lifestyle behaviour change using video observations. Methods: Professional caregivers (N = 14) were observed in daily work supporting adults with mild intellectual disabilities. Videos were analysed using the Coventry Aberdeen London Refined (CALO-RE-NL) taxonomy and BCTs utilised were coded. Results: Twenty one out of 40 BCTs were used by professional caregivers. The BCTs 'Information about others' approval', 'Identification as role model', 'Rewards on successful behaviour', 'Review behavioural goals' and 'Instructions on how to perform the behaviour' were most employed. Conclusion: Professional caregivers used BCTs to support healthier lifestyle behaviour of adults with mild intellectual disabilities. However, most promising of them as defined previous by professionals were rarely used by professional caregivers.