The Pagefield Sport team will be led by new partner Liam Parker and CEO Oliver Foster.
Pérez-Barbadillo will continue to work for and travel on the tour with 16-time Grand Slam champion Nadal, while his Rafa Nadal Academy by Movistar becomes a client of Pagefield.
The Spaniard worked for tennis governing body the ATP before working for Nadal, and has also had clients including top tennis players Novak Djokovic and Victoria Azarenka, as well as international footballers Alessandro del Piero and Esteban Cambiasso.
Another client of Pagefield Sport is Paula Radcliffe, a retired UK athlete who remains the fastest women's marathon runner of all time. Britain's fastest sprinter over 100m and 200m, Dina Asher-Smith, has also signed up, as have football match day lottery firm Funders Inc (formerly Match Plus) and esports channel Ginx Esports TV.
None of these five clients previously had specific PR agency support, although Asher-Smith is managed by Pace Sports Management.
Radcliffe, who now works as a pundit and broadcaster, and has been vocal on issues including doping and ethics at the IOC since, said: "I am very excited to be working with Pagefield Sport to promote the big issues on and off the track that are so important to me."
Referring to a new Families on Track initiative she is launching, she said: "I want to help others realise their potential through sport and to enjoy the health and wider benefits sports can bring to everyone. The team at Pagefield share my passion and determination but also have the experience and networks to deliver results."
Foster said: "The sporting world is a tough and heavily scrutinised environment - and it’s one that deserves the kind of discipline and rigour that we’ve been applying to our wider work in corporate PR and public affairs since 2010."
Other recent developments at Pagefield have included October's launch of Bell Pottinger spin-off Pagefield Global Counsel and the appointment of ex-Times journalist and Bell Pottinger director Philip Pank to Pagefield itself.
Since Parker joined the agency in September, work has included acting as the spokesman for the late Professor Stephen Hawking's family, with the agency working on his funeral.