Wasira served as Deputy Minister of Agriculture in the first phase Government under President Julius Nyerere and also served as the Deputy Minister for Local Government and later as the Minister of Agriculture and Livestock Development under second phase President Ali Hassan Mwinyi.

He was appointed as Minister of Water on January 4, 2006, when Jakaya Kikwete, who had been elected President, named his new cabinet.
He was then moved to the position of Minister for Agriculture, Food Security and Cooperatives on October 15, 2006, and on February 12, 2008, he was named Minister in the Prime Minister's Office for Regional Administration and Local Government.

On November 24, 2010, Wasira was named Minister of State in the President's Office for Social Relations and Coordination in the newly formed cabinet after the October 2010 elections.

Within the ruling Chama cha Mapinduzi, most recently he  was a member of the 370-member National Executive Committee (NEC), the highest policy and decision-making body of the ruling party.
He served in this position since 2007.
In November 2012, he was overwhelmingly re-elected by the party's National Congress to serve another five-year term.
 Also, in 2011, he was elected a member of the party's powerful 28-member Central Committee (CC)  He continued serving as a member of the Central Committee after being re-elected in February 2013 up to December 2017.
Wasira served as Deputy Minister of Agriculture in the first phase Government under President Julius Nyerere and also served as the Deputy Minister for Local Government and later as the Minister of Agriculture and Livestock Development under second phase President Ali Hassan Mwinyi.
He was appointed as Minister of Water on January 4, 2006, when Jakaya Kikwete, who had been elected President, named his new cabinet. He was then moved to the position of Minister for Agriculture, Food Security and Cooperatives on October 15, 2006, and on February 12, 2008, he was named Minister in the Prime Minister's Office for Regional Administration and Local Government.
On November 24, 2010, Wasira was named Minister of State in the President's Office for Social Relations and Coordination in the newly formed cabinet after the October 2010 elections.
Within the ruling Chama cha Mapinduzi, most recently he  was a member of the 370-member National Executive Committee (NEC), the highest policy and decision-making body of the ruling party. He served in this position since 2007. In November 2012, he was overwhelmingly re-elected by the party's National Congress to serve another five-year term.  Also, in 2011, he was elected a member of the party's powerful 28-member Central Committee (CC)  He continued serving as a member of the Central Committee after being re-elected in February 2013 up to December 2017.
Stephen Wasira