This paper discusses voter mobilisation and other election-related activities of Malaysian voters living, studying and working in Singapore in the context of Malaysia’s 13th general election (GE13). According to the World Bank, nearly 400,000 Malaysians reside in the city-state. Thus these figures represent a significant Malaysian voter pool based in Singapore. Efforts to mobilise these voters for general elections or other causes have political implications for both countries, which became apparent following Singapore-based Malaysians’ activities to encourage Malaysians to return home to cast their votes during the 13th general election. Singapore’s strict public assembly laws led to several legal issues related to the voter mobilisation and election campaign activities undertaken by Malaysians in the city-state. These legal issues became a source of friction between the two countries during the elections as government leaders and authorities on both sides of the causeway accused the other of interfering in domestic political matters. Given the growing number of Malaysians in Singapore and the likely repeat of Malaysian voter mobilisation activities in Singapore in the run-up to the fourteenth general election (GE14) in 2018, issues related to the election activities of Malaysian voters in Singapore stand to be another set of factors that will shape the health of bilateral relations between these two countries.