He joins the business on 14 March.
Mclaughlan brings with him more than 25 years of retail industry experience. Prior to 2012 when he became MD at Toys'R'Us, he held senior executive roles at Marks and Spencer, Woolworth's South Africa and Asda.
Mclaughlan takes over from Kevin Bradshaw. Wyevale said in a statement Bradshaw had "provided great leadership as CEO during the turnaround, doubling EBITDA and setting the business on course for its next phase of growth".
Bradshaw will remain with the business for the next few months to ensure a smooth transition, after which he will be "exploring other leadership roles" within the Terra Firma portfolio companies.
Stephen Murphy, chair of Wyevale Garden Centres, said: "I would like to thank Kevin for his important contribution over the past three years. Under Kevin's leadership, Wyevale has cemented its position as the UK's largest garden centre retailer.
"We have established a clear national brand, grown the business, modernised our stores to make them even more appealing to customers, expanded our product ranges and developed an award-winning restaurant offer.
"Roger joins us with a fantastic track record in leading retail businesses and he is perfectly placed to build on the success so far and drive further value as the business enters the next phase of its transformation."
Justin King, vice chairman and head of portfolio businesses at Terra Firma, said: "I am delighted that Roger is joining Wyevale and I am confident that he will build on Kevin's successful turnaround of the business so far. I am looking forward to working with him and the team to execute the next phase of our transformation strategy as we transform our supply chain and IT to provide a solid platform for future growth."
Roger Mclaughlan: said: "I'm delighted to be joining the business at such an exciting time and I look forward to working with Justin, Stephen and the team."
Kevin Bradshaw said: "We have achieved a great deal over the past few years and the business I hand over to Roger today is in a much stronger place. I look forward to working with him to ensure a seamless transition and am absolutely confident that he will continue to harness the future growth of this outstanding business."