Chief executive Stephen Jacob is confident the trend will continue as the organisation looks to expand its influence within the sector.
He said: “The PROMPT register has developed into an essential facility serving the pest control sector and membership has grown significantly year on year.
“By acting as proof of expert credentials, it has helped to establish a better definition of a professional pest controller, which was much needed in the UK, and it’s great to see that message getting through.
“We signed up our 1,000th member in 2010, so to have reached more than 4,000 just over six years later shows a significant level of growth.
“The challenge for us will be to maintain that level of progress and I’m confident that our strategies will continue to deliver.”
The launch of a rodent-specific category in 2016 has so far attracted more than 700 new members and, with further developments in the pipeline, Mr Jacob insists PROMPT has a bright future.
He added: “We think more than half of the professional pest technicians in the UK are now members of our organisation and that’s fantastic news.
“But we’re determined to deliver further benefits to existing members and build awareness of the register and the advantages that it provides.
“We’re accepting new technicians every week, providing they meet the criteria of course. But we also run stalls at major events and exhibitions where we talk directly to potential new members, explain what we’re all about and how membership of PROMPT can help their business.
“We signed up a host of new members at Pest Tech in November and we’ll be at PestEx 2017 in London in March.”
Mr Jacob plans to maintain the progress of the register by focusing on the value of membership.
He said: “I’d like to think most of our members feel they’re already getting a lot out of their registration and that it’s not just a box-ticking exercise.
“The identity card delivers significant value as it helps professional technicians to stand out from the crowd. But we’re now doing more for our members and there’ll be other developments in future.
“Last year we launched a mobile phone app which is a digital version of the identification card. It makes it quick and easy for members to register at events, log participation in training activities and collect CPD points.
“We’re in the middle of a project to improve the website and will build new pages which spell out the benefits of using PROMPT members both to businesses and domestic customers.
“We have an ongoing campaign to help raise the profile of the register and the benefits of employing PROMPT members and the quarterly newsletter will keep members and supporters updated on our news and activities.”