Ben-Eliezer served in the Israel Defense Forces as a career officer, serving as a commander in the Six-Day War (1967) and the Yom Kippur War (1973). He was wounded in the War of Attrition. Ben-Eliezer graduated from the IDF Command and Staff College and the Israel National Defense College. He was a member of the IDF Military Mission to Singapore (1970-73). In 1977 he was appointed Commanding Officer in Southern Lebanon, serving as the IDF liaison between Israel and the Christians in Lebanon. Ben-Eliezer served as Military Governor of Judea and Samaria (1978-81) and as Government Coordinator of Activities in the Administered Areas (1983-84).

In 1984 Ben-Eliezer was elected to the Knesset. He has served on the Knesset Foreign Affairs and Defense Committee (1984-92, 1996-99); Labor and Social Welfare Committee (1984-1988); and House Committee (1974-1988). He also chaired the Israel-Canada Parliamentary Friendship League (1988-92).

Benjamin Ben-Eliezer served as Minister of Construction and Housing from 1992-1996.

In July 1999 he was appointed Minister of Communications and Deputy Prime Minister, and in August 2000 was also assigned the Construction and Housing portfolio, serving in these positions until March 2001.

Benjamin Ben-Eliezer served as Minister of Defense from March 2001 until October 2002, when he resigned from the government together with the other Labor ministers.

In January 2005 he was appointed Minister of National Infrastructures. He resigned his post at the end of November with the resignation of Labor from the government.

Benjamin Ben-Eliezer served as Minister of National Infrastructures from May 2006 until March 2009, and as Minister of Industry, Trade and Labor from March 2009 until his resignation in January 2011.

He is married and the father of five.