Background: Intensive multidomain interventions can slow cognitive decline but may not be affordable or accessible. We evalauted a fully remote, low-intensity, multidomain intervention in people with Subjective Cognitive Decline (SCD) or Mild Cognitive Impairment (MCI). Method: We conducted a two-arm, single-blind randomised controlled trial comparing our MyCoach intervention with an active psychoeducation control. Participants were aged ≥65 years with SCD or MCI. The 12-week intervention included a 6-session interactive e-learning program, clinical exercise and dietary advice, BrainHQ cognitive training and a booster session. Outcomes were assessed at 3, 6 and 12-months. The primary outcome was change on the ANU-ADRI risk score at 12 months. Results: Of 325 eligible participants (160 intervention, 165 control), 32% were from regional areas. At 6 months the ANU-ADRI score was lower in the intervention than control group (diff= -1.07 (95%CI:-1.89 -0.25; p = 0.011). At 12 months, the ANU-ADRI score was lower in the intervention group compared with control (diff= -0.62 (95%CI:-1.45, 0.21; p = 0.14). In a predefined subgroup with higher baseline lifestyle risk (ANU-ADRI ≥8; n=139), the intervention led to a clinically meaningful reduction in ANU-ADRI at 6-months compared with control (diff= -1.78 (95%CI:-3.06 to -0.51; p=.006) but this was not sustained at 12-months. Adherence was high, with 70% completing all modules and a further 13% completing five of six. There were no intervention-related adverse events. Conclusion: Low intensity, remotely-delivered non-pharmacological interventions are feasible for adults with SCD and MCI, but longer duration of interventions are needed to maintain benefits.