As part of the move, chartered town planner Richard Raper has joined the national consultancy's Leeds office as a consultant.
Raper's two employees, both Royal Town Planning Institute licentiate members, have also joined DPP's Leeds team: Haris Kasuji as a principal planner and Graham Whiteford as a senior planner.
RRP acts for bookmakers Ladbrokes across the UK and Ireland and also counts major high street banks among its clients. Raper is working to bring RRP's clients over to DPP, as well as acting in a wider business development role, the consultancies said in a statement.
According to Planning's 2011 consultancy survey, DPP employed 61 chartered town planners in the UK and had a fee income of £8.9 million in 2010/11.
Neither DPP nor RRP was willing to disclose details of the fee DPP paid to acquire the Leeds firm, or to provide details of RRP's fee income in 2010/11.
DPP chairman Bob Robinson said the acquisition would bolster the consultancy's income stream. He added: "We are always on the lookout for opportunities to broaden our client base."
Richard Raper said: "Although we are only a small practice, we have some major blue-chip clients and we're strongly proud of what we do.
"I wanted to make sure the business would continue. DPP's complementary working culture and approach means we see strong mutual benefit in this coming together for our team and clients."