Barrow, a senior counsel, is one of Belize's successful attorneys and has appeared in several high-profile cases. He began his legal work in the law firm of uncle Dean Lindo in 1973 and became a partner there in 1977. He would eventually leave to form his own law firm, Barrow and Williams (with Rodwell Williams) until he vacated office prior to the 2008 general elections, although he remains titular senior partner. Among his firm's more controversial clients is Lord Ashcroft and the businesses he is connected with, particularly the Belize Bank and at one time, Belize Telemedia Limited, formerly Belize Telecommunications Limited.
In December 1983 Barrow entered electoral politics as a candidate for Belize City Council elections, which he won as part of a nine-man slate. Before that year's redistricting, in 1984 Barrow was preselected as the UDP candidate for Collet but after redistricting chose to contest the newly created Queen's Square constituency instead, as was his prerogative under UDP party rules. In the ensuing election Barrow handily defeated Ralph Fonseca of the People's United Party. Soon after he was appointed to the first Manuel Esquivel Cabinet as Attorney-General and Minister of Foreign Affairs.
In the 1989 general election, Barrow defeated Thomas Greenwood but his party lost the election. Barrow continued in his law practice. In 1990, he became deputy UDP leader under Esquivel after the death of Curl Thompson. In 1993, Barrow won his third straight general election and returned to the Cabinet in the posts he held from the previous administration in addition to Minister of National Security. His detractors called him "Minister of Everything" during this period because he was a particularly high-profile spokesman for the Esquivel government.
After the UDP's devastating 1998 election loss in which he was one of only three UDP winners, Barrow was elevated to UDP party leader and Leader of the Opposition, succeeding the defeated Esquivel. Barrow presided over the smallest oppositions (three and seven respectively) in the House of Representatives since 1974 and ever in the UDP's history. Barrow was reelected in 1998 and 2003 by closer margins than his previous elections over attorney Richard "Dickie" Bradley. He has since been re-elected by comfortable majorities.
Barrow is currently the most senior member of the UDP delegation in the Belize House as well as the Area Representative with the longest tenure of uninterrupted service. Among current Area Representatives, only Said Musa has a longer cumulative time in office.
The UDP won a massive victory, with 25 out of 31 seats, in the general election held on 7 February 2008, and Barrow was sworn in as Prime Minister on 8 February. He is the country's first black Prime Minister. He announced his Cabinet, including himself as Minister of Finance, on 11 February.
The UDP won a reduced majority in the 2012 general election and Barrow started his second term as Prime Minister on 9 March 2012. He announced his cabinet, including himself as the Minister of Finance and Economic Development, on 12 March 2012.
Barrow led the UDP to a third consecutive general election victory in November 2015, however he stated the election would be his last as party leader.
Citing health issues, Barrow said he will step down as prime minister no later than the end of 2019 and hinted he could do so earlier. He will also stand down from his House seat in Queen's Square at the next general election, endorsing his sister Denise "Sister B" Barrow to succeed him.
Barrow has four children. The oldest is rapper Jamal "Shyne" Barrow, born 8 November 1979. (Shyne was born out of wedlock; his mother is the sister of Barrow's political colleague, Michael Finnegan). His second son Anwar runs a small-scale lending institution. His daughter Deanne practises law out of her mother's (Barrow's first wife Lois Young) firm.
Barrow was married a second time 7 February 2009 in Savannah, Georgia to his long-time girlfriend Kim Simplis. They have one daughter, Salima.
Barrow attended St. Michael's College in Belize and the University of the West Indies, Cave Hill, Barbados (LL.B. 1973); Norman Manley Law School, Mona, Kingston, Jamaica (Certificate of Legal Education, 1975); University of Miami School of Law (LL.M., 1981); University of Miami (M.A. International Relations).