The name change takes effect in May 2017.
Mouchel Consulting, which was acquired in October 2016, will also become WSP in July when it is fully integrated with the wider business.
The name currently used on the Toronto Stock Exchange remains unchanged as WSP Global Inc.
UK chief executive Mark Naysmith said: “WSP is a successful story of global growth. We have decided to change our name after speaking to our people and our clients extensively. Our conversations with clients showed they have a genuine curiosity about us and the services we provide. For our 7,100 people in the UK, being WSP will allow us to focus on our shared future, combined talent and common vision as one of the country’s fastest growing engineering professional services consultancies.”