He was born in a small suburb southwest of Baltimore workers as the son of a paralegal Nancy and Bob Ehrlich, Sr., a former Marine infantryman and veteran of the Korean War, which for 37 years worked as a car dealer a Ford agency in Arbutus. Robert Ehrlich gained his academic and athletic experience first at the Gilman School in Baltimore and later at Princeton University. There he was employed in his first year as a senior as captain of the football team.
After he had passed his law degree from Wake Forest University in 1982, he joined the Baltimore law firm of Ober, Kaler, Grimes and Shriver.
In November 1986, he began his political career when he was elected as a representative of the 10th district (Baltimore County) in the House of Representatives from Maryland. After eight successful years in the legislature of his state Ehrlich in 1993 announced his candidacy for the House of Representatives of the United States. At this time he was an absolute novice at the federal level, newlyweds with Kendel Sibiski, who worked as a public defender in Anne Arundel County. During the election campaign he promised to lower taxes for the working Americans, a strengthening of the national defense as well as greater support for American seniors and veterans. He also called for an improvement in elementary education. In contrast to the usual rules Ehrlich was elected by a two -thirds majority as a member of the second constituency in the Congress.
During the following eight years in the House of Representatives Ehrlich worked in the fulfillment of his promises, which, given the policy President Bill Clinton had to be easy for him, because this government program to meet his inflated both the defense budget and also not effective going against the tax burden. On the other hand Ehrlich supported all efforts on the way to a balanced federal budget. Because of its interest in the supremacy of the Republicans in Congress took Ehrlich soon key positions in the Energy and Economic Committee, where he worked in the subcommittees on health, telecommunications and the Internet, among others.
Ehrlich is considered active supporter of the booming especially in Maryland Biotechnology and Biomedicine, which he, a long time up to George W. Bush's change of course took an outsider within the Republican Party, which always had ethical reservations about genetic engineering. On the other hand Ehrlich never forgot his roots, which lay in a working class suburb, and actively supported the interests of the steel-using communities of Maryland. As a result, he was elected in November 2000 for the fourth and final time with 70 % of the votes in Congress.
With the election of George W. Bush as President of the United States in the same year Ehrlich's career reached a new dimension: As a trusted ally of Bush, especially in matters of the steel industry, the small business and youth training, Ehrlich announced on 25 March 2002 its governor candidacy. During his very active campaigning across the state, he stressed his background as a Marylander, promised the budgets of all schools in the state to increase, reduce to towering budget crisis and amplified to provide the Chesapeake Bay nature reserve. On 5 November 2002 was elected Robert L. Ehrlich for the first Republican Governor in Annapolis for 36 years.
In the gubernatorial elections of 7 November 2006, he lost the only incumbent, the election against his Democratic challenger Martin O'Malley. In November 2010 he joined again to O'Malley, but lost this turn.