Bottomley, who is currently the planning director, will report to Jim Carroll, the chairman of BBH UK, and take responsibility for running the UK planning department. He replaces Rachel Hatton, who becomes the planning director on Audi and Robinsons.
Carroll said: "BBH has a great heritage of finding and developing strategic talent. I'm confident Jonathan will continue this tradition."
In his newly created role, Gonsalves, the director of engagement planning, will run the UK department reporting to Kevin Brown, the global director of engagement planning.
Brown added: "The establishment of engagement planning to bring channel thinking into the creative development agenda is part of BBH's future vision. Jason's contribution to the success of building the discipline in London has been immense and he thoroughly deserves this promotion."