This is the protocol for a Campbell Systematic Review. This review will address two aims: (1) A qualitative synthesis of literature on the composition of online far right propaganda, and (2) A quantitative synthesis of literature examining the impact of exposure to online far‐right propaganda on audiences. These syntheses will be guided by the following specific objectives: (i) What is the content (i.e. themes) of online far‐right propaganda, and how does this differ across ideological subgroups? (ii) What is the structure of online far‐right propaganda, and how does this differ across ideological subgroups? (iii) What is the context of these messages (i.e., where, when and by whom were they posted?) (iv) What impact does exposure to online far‐right propaganda have on audiences with reference to the radicalisation of opinion and/or action?