The charity appointed the agency following a competitive pitch against MediaCom and Seven Stars.
The appointment takes effect immediately and takes in both supporter acquisition and brand marketing. The account was previously handled by Carat.
Sarah Fitzgerald O’Connor, supporter acquisition manager at the charity says: “We chose the JAA / Agenda21 team because they showed a strong understanding of our issues, the innovation and attention to detail to help transform the efficiency of our DRTV programme and a passionate approach that fits both our culture and strategic needs. We are looking forward to working with them to deliver a step change in acquisition effectiveness and brand consideration.”