"I've known Mike a number of years ... Governor Johanns is a man of action and a man of complete integrity," Bush said in announcing his nominee.
If approved by the Senate, Johanns would succeed Ann Veneman as 28th secretary of the USDA. Veneman originally had said she was interested in continuing her post within the Bush administration, but announced her resignation Nov. 12.
Johanns thanked Bush for the opportunity and added he looked forward to working to promote the administration's agenda.
"It is a privilege for me to be nominated to serve in your Cabinet," he said in the White House nomination ceremony. "I have enormous respect for you and for the work that you are doing for our country."