Chastain has been assistant chief of wildlife management.
Knoedl, with the rank of colonel, has been chief of enforcement.
They are replacing Don Brazil, who resigned earlier this year to return to his native Mississippi, and Scott Henderson, former director of AGFC, who retired.
Chastain and Knoedl will work directly under director Loren Hitchcock. Mike Armstrong continues as deputy director.
Knoedl is a native of Scott in Pulaski County and graduated from Sylvan Hills High School.
He joined The Game and Fish Commission in 1985 as a wildlife officer after completing the agency's cadet course.
He was a wildlife officer in Perry, Saline, Pulaski and Dallas counties for 21 years and was selected as the state's Wildlife Officer of the Year in 1993.
In recent years, he was promoted to lieutenant and a district supervisor, then to major and in 2008 to colonel and head of the Enforcement Division.
Chastain is a native of Lewisville in Lafayette County and graduated from Lewisville High School.
He received a bachelor of science degree in zoology from the University of Arkansas and joined AGFC as a biologist in 1979.
He worked in the agency's turkey restoration program and on its quail management team before becoming an assistant district wildlife supervisor.
He was named Acres for Wildlife Biologist of the Year in 1994. He moved up to district wildlife supervisor for the Ouachita Mountain region and was named assistant chief of wildlife management in 2004.
Hitchcock said of the new appointments, "I was fortunate to find two employees who have a cumulative total of 59 years of loyal and dedicated service to our agency at various ranks within their respective divisions. Replacing the positions they are leaving will be uniquely as important, as we must have knowledgeable, confident, loyal and dedicated leaders in place at all of our managerial levels. I have no doubt that Mike Knoedl and Ricky Chastain will meet the new challenges and responsibilities with all their commitment and eagerness as they have their whole careers." Knoedl and Chastain will continue to work out of the AGFC's Little Rock headquarters.