The presidency said he died while receiving treatment at the Jakaya Kikwete Cardiac Institute in Dar es Salaam.
Tanzania Vice President Dr Philip Mpango made the announcement through the national television, TBC.
Lowasa, 70, served as Tanzania Prime Minister from 2005 to 2008 under President Jakaya Kikwete.
He went into record as the first Prime Minister to have been forced to resign.
Lowasa unsuccessfully vied for the presidency in 2015 against the late former President John Magufuli of CCM.
He ran as an opposition candidate on Chama cha Demokrasia na Maendeleo (CHADEMA) ticket after the ruling CCM failed to select him as its candidate for the polls.
Born on August 24, 1953, Lowasa was the fourth child of herdsman Ngoyai Lowassa who worked part-time for the colonial government.
He has a long-running history in both parliamentary and government affairs.
Besides being an MP, Lowasa previously served as Minister of State in the Prime Minister’s Office during President Ali Hassan Mwinyi’s second term.
In 1997, he was appointed Minister for State in the Vice President’s Office for Environment and Poverty.
In 2000, he was appointed Minister of Water and Livestock Development.
He backed Kikwete for the presidency in 2005 after failing to clinch CMM’s nomination in the 1995 elections.