The consultant has paid £2.5 million in cash to the founder shareholders of MG Bennett which has a 30-strong team based in Rotherham, South Yorkshire.
MG Bennett specialises in mechanical and structural engineering and has a strong track record in delivering solutions to the nuclear industry, having developed particular expertise in lifting and handling nuclear-related materials.
MG Bennett also works in the aerospace, oil and gas, power, environmental and rail sectors.
The acquisition enhances Atkins' nuclear capability and its expertise in mechanical design.
Atkins currently has more than 250 staff working across the nuclear industry and supports its clients in the areas of decommissioning, current generating capacity, waste storage and the new-build programme.
Chris Ball, director of the nuclear business at Atkins, said: “This acquisition strengthens our business as we seek to enhance our offering in the mechanical design sector and to ensure we have the skills in place to respond to increased demand in the new build, decommissioning and generation markets.”