This study examines how online activism affects dyadic representation in the UK Parliament.

Data & Methods: New data from the UK e-petition system reveals that constituent petition support significantly increases MPs' likelihood to advocate for their views during parliamentary debates. Even when addressing identical policy issues without an active campaign, MP responsiveness is amplified by digital advocacy tools.

Key Findings: The analysis demonstrates a clear causal link between high petition support and increased MP advocacy in official discourse. However, this response pattern shows notable constraints based on party discipline requirements - MPs coordinate their positions accordingly regardless of constituent sentiment.

Electoral Context Matters: Responsiveness to online constituents varies substantially depending on electoral competition levels. In safer seats with lower turnover rates among voters, MPs show considerably stronger correlation between petition support and advocacy effort compared to more competitive districts where such alignment is less pronounced.

Policy Implications: These findings suggest e-petitions create a tangible pathway for citizens' views reaching elected officials while also highlighting institutional factors that shape this relationship. The results offer nuanced insights into how digital political tools interact with traditional parliamentary dynamics.