The COVID-19 disease was declared a global pandemic by the 11th of February 2020, presenting a major threat to public health worldwide. Success in the battle against COVID-19 depends on public adherence to control measures. Their adherence is greatly affected by their knowledge, perceptions, and practices; therefore, the aim of this study was to assess and understand the knowledge, perceptions, practices, and trusted information sources of COVID-19 among Irish residents. A quantitative survey was performed by means of an online questionnaire, which comprised five sections to collect data regarding demographics, knowledge, perceptions, practices, and information sources. A total of 1007 participants completed the online survey between February and March 2021. The majority of respondents (69.4% female and 30.3% male) had a correct rate of knowledge (88%) and practices (68.1%), with health organisations being the most trusted information source (70.7%); 87.4% understand good mask etiquette. Only 53.7% agreed that closing schools or mass gathering events are an effective way to reduce the spread of the virus, while 81.3% are aware that COVID-19 is more severe than the flu; 64% of respondents said that the pandemic has negatively affected their mental health. It was observed that a higher level of knowledge is positively correlated with good practices. The study concludes that most of the respondents have shown a good level of knowledge and right practices towards the COVID-19 pandemic, and that the higher the level of knowledge of individuals, the better the COVID-19 safety practices are that they perform. It has been observed that the continuous improvement on an individual’s level of knowledge of COVID-19 is essential to maintain good safety practices and reduce the spread.