His DUP colleague Nelson McCausland moves from his role as minister of culture, arts and leisure to become the new social development minister.
Attwood, a former solicitor, had served in that role since May 2010 until today’s appointment.
He was elected to the assembly in June 1998. As environment minister he will take responsibility for the natural and built environment, land use planning, plus local government.
McCausland will take responsibility for housing, community and voluntary sector development, urban regeneration and social legislation.
The Ulster Unionist Party’s Danny Kennedy has been announced as minister for regional development, while Dr Stephen Farry, of the Alliance Party, will become minister for employment and learning.
Arlene Foster, of the DUP, will continue her role as enterprise minister.