This article analyses nearly one million petitions received by the House of Commons to reveal a culture of petitioning that recast the political culture of modern Britain and Ireland. It argues, first, that petitions provided a much more regular and continuous form of interaction between people and Parliament than elections. Second, petitioning–meaning the practices associated with the drafting, signing and presentation of petitions–enabled a vibrant, performative public politics. Third, petitions and petitioning were relatively open, inclusive forms of political participation since all British subjects enjoyed the formal right to petition. We examine the role of formidable campaigns of mass mobilisation, but also humble appeals of marginalised individuals. Our data has significant implications for our understanding of the nationalisation, organisation, and popularisation of politics in this period. We argue that attention to petitions helps us to decentre parliamentary elections as the principal connection between local and national politics. Indeed, petitioners responded to the shifting boundaries between the central and devolved state in deciding to which authorities they would direct petitions. Petitioning campaigns pioneered the mass, organised, national movements that would gradually emerge as the hallmark of stronger political parties. This did not undermine petitioning. However, the consequent growth of disciplined parties strengthened executive power, at the expense of parliamentary government, redirected petitions from the Commons. Furthermore, the continuing expansion of petitioning alongside extensions of the franchise suggests that petitions did not function as an ersatz ballot. Rather, petitions and debates between parliamentarians and petitioners over the meaning of growing lists of signatories suggest that petitioning catalysed a range of other forms of participation and hence forged an ever more popular politics.