Jonathan is a New Zealander of Samoan decent. He grew up in Dunedin and studied law and music at the University of Otago. Jonathan graduated with a Bachelor of Laws in 1999. He then completed three years study at the Royal College of Music (RCM) in London, earning the College's highly esteemed gold medal. In his first year at RCM Jonathan completed a postgraduate certificate, and then gained a place on the two-year RCM London Royal School's Opera Course, now known as the RCM Benjamin Britten International Opera School.

Jonathan made his first recording with EMI Classics in 2001 on the Debut label with the albumn Jonathan Lemalu, Roger Vignoles. Songs: Brahms, Faure, Finzi, Schubert. He won the prestigious Gramophone award for Best Debut Recording at the 2002 awards:

"Every so often a musician arrives on the scene with a talent so richly endowed that the musical world sits up and takes note. The New Zealand-born Samoan Jonathan Lemalu is one such." - Gramophone.

Jonathan released his first major EMI recording in 2005, a selection of popular songs titled Opera Arias. In 2009, Jonathan featured on the album Britten: Billy Budd (engineered by Neil Hutchinson & Jonathan Stokes), which won Best Engineered Album, Classical, in the 2010 Grammy Awards.

Jonathan was one of four artists selected to receive a $10,000 donation by 2008 Arts Foundation Award for Patronage recipients Gillian & Roderick Deane. Jonathan's father Foalima Lemalu accepted the award on Jonathan's behalf, saying that is was a ‘proud moment' for him and his wife.

Critics and audiences have noted Jonathan's stage presence, interpretive ability, his power, warmth and captivating voice. Jonathan has established himself on the international stage, performing mainly in America and also throughout Europe, Australia and New Zealand.

On Jonathan's performance in the 2010 production of Moby Dick with the Dallas Opera, critic Anne Midgette wrote:

"The opera's first scene opens with Queequeg, played by Jonathan Lemalu, making ritual invocations in a foreign language and a dark, deep, almost other-worldly voice, chanting among the sleeping bodies of the other sailors in the hold... Lemalu brought authority, vocal richness, and even the right ethnicity (he is of Samoan descent) to the part, acting as a kind of moral compass standing slightly apart from the other crewmen."