Introduction This study aimed to determine the validity and reliability of video-based telerehabilitation assessments in patients with heart failure. Methods Seventeen consecutive participants (mean age 69 years, SD 12 years and 88% males) undertook assessments of three functional tests via both telerehabilitation and face-to-face approaches, on the same day. The assessment order was randomised and conducted by independent assessors. Outcome measures included functional tests: timed up and go (time), six-minute walk (distance), grip strength (kilograms); system usability scale to rate participant experience with telerehabilitation assessment; and number of technical issues encountered. Validity and inter- and intra-rater reliability of telerehabilitation assessments were examined using limits of agreement, intra-class correlation coefficients (ICC), and paired t-tests. Results The limits of agreement for telerehabilitation assessments were within the clinically acceptable limits for timed up and go and grip strength. Telerehabilitation assessments for all functional tests were strongly associated with face-to-face assessments, with ICCs of between 0.85 and 0.96. Inter- and intra-rater reliability of telerehabilitation assessments for all functional tests were excellent (all ICC > 0.95). The mean (SD) system usability scale score was 85 (15)/100. Some incidences of Internet drop-outs, video freezing and auditory fading occurred. Discussion The use of telehealth for the assessment of functional exercise capacity appears to be valid and reliable in patients with heart failure.