Health communication offers an important means for patients to make informed decisions for illness self-management. We assessed how the level of engagement with selected health information at baseline is associated with the adoption and maintenance of lifestyle behaviours at a 5-year follow-up in people with multiple sclerosis (MS). Non-engagers were compared to engagers of information delivered online and print (medium), and with engagers who additionally attended a live-in workshop (high). Engagement was assessed against lifestyle behaviours by log-binomial regression. Information engagers had higher education, and were less likely to have severe disability, clinically significant fatigue, or obesity. Medium and high baseline engagement was associated with adopting healthy behaviours for omega 3 supplementation (RR = 1.70; 95%CI: 1.02–2.84), physical activity (RR = 2.16; 95%CI: 1.03–4.55), and dairy non-consumption (RR = 3.98; 95%CI: 1.85–8.56) at 5 years; associations were stronger among high engagers. Only high baseline engagement was associated with maintaining behaviours from baseline to 5 years, specifically for omega-3 (RR = 1.26; 95%CI: 1.06–1.49) and vitamin D supplementation (RR = 1.26; 95%CI: 1.04–1.54) and dairy non-consumption (RR = 1.47; 95%CI: 1.03–2.10). Health communication that includes face-to-face information delivery and practical tools for implementation in daily living may be optimal for adopting and maintaining lifestyle behaviours in people with MS.