Hashtag campaigns on social media enable users to express their sentiments on various issues and mobilize people to be part of a movement or cause; they have been used effectively by disenfranchised members of society against powerful elites. While some are of the opinion that online campaigns are ineffective due to 'slacktivism', such campaigns can spill over to offline protests, especially if there are strong emotions such as anger, or a sense of injustice or social deprivation, spurring people on. The earlier hashtag campaigns in Malaysia - #AntaraDuaDarjat (#BetweenTwoStatus) and #DengkiKe (#AreYouJealous) - were expressions of unhappiness over perceived double standards in the enforcement of COVID-19 public safety protocols. Later hashtag campaigns such as #KerajaanGagal (#FailedGovernment), #KerajaanZalim (#CruelGovernment) and #KerajaanPembunuh (#MurdererGovernment) became increasingly negative as public disenchantment grew due to the government's weak handling of the pandemic and the consequent economic fallout. Public frustration that manifested itself in the #BenderaHitam (#BlackFlag) and #Lawan (#Protest) movements soon transitioned into offline campaigns and protests against the government. Apart from political hashtag campaigns, there were also welfare movements such as #KitaJagaKita (#WeTakeCareOfOurselves), #BenderaPutih (#WhiteFlag) and #RakyatJagaRakyat (#CitizensTakeCareOfCitizens), which enabled Malaysians to help those affected by the COVID-19 lockdowns, by rendering food aid and other assistance. A key conclusion of this study is that online hashtag campaigns have served as early warning of trending public sentiment. They also have the potential to hype up emotions online and subsequently galvanize support for offline campaigns and protests. As #Lawan and #BenderaHitam showed, these can have direct political outcomes.