Northey was born and raised in Ballarat, Victoria. His father Robert (Bob) Northey is a retired university administrator and former president of the Ballarat Symphony Orchestra and his mother Wendy is a forensic psychologist and pianist. His uncle is the retired AFL football player and coach John Northey.
He attended Ballarat Clarendon College where he studied flute, clarinet and saxophone with Barry Currie and arranging with Graeme Vendy, and where his skills as a saxophonist, clarinettist and flautist were first developed; in his early years he also played piano, trumpet and violin. At 12, he won prizes in Ballarat's Royal South Street Eisteddfod for performances on flute and saxophone. During his teenage years he began working professionally in local pit orchestras in Ballarat for musical theatre and operetta productions. After school he moved to Melbourne, where he worked as a freelance musician, composer and arranger for close to ten years. During this time he was an active recording session musician and also performed with the Melbourne Symphony Orchestra, the Australian Pops Orchestra and the Australian Showband. He appeared as a soloist with the Australian Wind Orchestra on their tour of Japan and Hong Kong in 1990. In 1998 he toured Australia and the United States with guitarist Tommy Emmanuel.
He is currently based in Melbourne with his wife (the horn player Joanne Montesano), and two children.
In 1996 Northey commenced performance studies in classical saxophone at the University of Melbourne Conservatorium of Music, graduating in 1999 with First Class Honours. It was only in the final year of his degree, at age 29, that he turned to conducting. This occurred under the mentorship of John Hopkins, who encouraged him to be the first candidate for his new Master of Music in Conducting degree at the Victorian College of the Arts and Music. He graduated in 2002.
In 2001 he won the Nelly Apt Scholarship for study in Israel. The same year he won the Symphony Australia Young Conductor of the year competition, marking the first time the two most prestigious Australian conducting prizes had been won by the same person in the same year. Part of the prize for the latter award was the opportunity to study in Sydney with Jorma Panula, under the aegis of the Symphony Australia Conductor Development Program.
In 2002 he was the highest placed applicant to the Orchestral Conducting Course at the Sibelius Academy in Helsinki, Finland. He studied there for three years under Leif Segerstam and Atso Almila.
In 2004 his diploma concert with the Sibelius Academy Symphony Orchestra was awarded the international jury's highest possible mark. The program included the European premiere of Brett Dean’s Amphitheatre.
He completed his tertiary studies in 2006 as a guest student in Jorma Panula's class at Sweden's Royal College of Music, Stockholm.
In 2007 he was chosen from a worldwide field as one of three participants in the International Conductor's Academy of the Allianz Cultural Foundation. This involved a year-long mentorship with the London Philharmonic Orchestra (LPO) and the Philharmonia Orchestra, with conductors Christoph von Dohnányi and Vladimir Jurowski. This culminated in a performance of Stravinsky's Symphony in C in June 2008 at the Royal Festival Hall in London.
In 2002 Ben Northey first displayed his interest in contemporary music by conducting the world premiere of Mark Elliott's Concerto for Chinese Sheng and Orchestra with the University of Melbourne Symphony Orchestra.
From 2002 to 2006, he was Resident Guest Conductor of the Australian Pro Arte Chamber Orchestra (later renamed the Melbourne Chamber Orchestra, of which he was Principal Guest Conductor 2007-10).
His major professional conducting debut came in 2003 with the Melbourne Symphony Orchestra, in a concert at the Myer Music Bowl that included Beethoven's 6th Symphony.
In 2005 he made his official European conducting debut with the Mozarteum Orchestra Salzburg. He was also a visiting artist at the Australian National Academy of Music and a guest lecturer in conducting at the University of Melbourne.
Since returning to Australia in 2006, Northey has been a regular guest conductor with all the Australian state symphony orchestras. He has also led opera productions including Turandot, Carmen, L'elisir d'amore, The Tales of Hoffmann, La sonnambula, Sweeney Todd, Orpheus in the Underworld, Don Giovanni and Così fan tutte, for companies such as the State Opera of South Australia, Opera Australia and New Zealand Opera and the ballet A Midsummer Night's Dream for the Queensland Ballet.
In 2006 he worked with Hilltop Hoods and the Adelaide Symphony Orchestra to create an orchestral take on the Hoods' platinum-selling album "The Hard Road Restrung". This unique collaboration won an ARIA Award. His orchestral arrangements have been used by Tim Minchin, k.d. lang, The Whitlams and Dan Sultan.
In 2009 Northey was appointed Conductor of the Melbourne Symphony Orchestra (MSO)'s Education Program.
In 2011 he was appointed Associate Conductor of the MSO (officially the Patricia Riordan Associate Conductor Chair) In 2017 the position was extended to the end of the 2017 season. This position was created especially for Northey, and is the only associate conductor position in any Australian state orchestra. In 2012 he was a last-minute replacement when Scottish conductor Donald Runnicles fell ill before an MSO Master Series concert, which included Mahler's 4th Symphony and Shostakovich's Violin Concerto No. 1 performed by Julian Rachlin. He now conducts the popular MSO Town Hall concert series.
Other orchestras he has conducted include the London Philharmonic Orchestra, Tokyo Philharmonic Orchestra, Malaysian Philharmonic Orchestra, National Symphony Orchestra of Colombia, Hong Kong Philharmonic Orchestra, Sydney, Queensland, Adelaide, West Australian and Tasmanian Symphony Orchestras, Australian Opera & Ballet Orchestra, Orchestra Victoria, Moscow Symphony Orchestra, Finnish Radio Symphony Orchestra, Israel's Haifa Symphony Orchestra, the Sodra Halsinglands Orkesterforening, Stockholm's Futurum Ensemble Sinfonietta, London's Southbank Sinfonia, and the New Zealand, Auckland and Christchurch Symphony Orchestra.
He has collaborated with artists including Maxim Vengerov, Piers Lane, Emma Matthews, Alban Gerhardt, Marc-André Hamelin, Amy Dickson, William Barton, Slava Grigoryan, Karin Schaupp, Julian Rachlin, Arnaldo Cohen, Karen Gomyo, Johannes Moser, k.d. lang, Patti Austin, James Morrison, Kurt Elling, Barry Humphries (as Dame Edna Everage narrating The Carnival of the Animals), Tim Minchin (in "Tim Minchin versus the Melbourne Symphony Orchestra" tour), Sting, Tori Amos and The Whitlams.
Contemporary compositions he has premiered include works by Peter Sculthorpe, Brett Dean, Elena Kats-Chernin, Matthew Hindson, and Brenton Broadstock.
On 5 November 2014 he was seen by a national television audience when he conducted the Sydney Symphony Orchestra and Sydney Philharmonia Choir in the Sydney Town Hall at the State Memorial Service for the late former Prime Minister Gough Whitlam.
He is Co-Artistic Director with Paul Grabowsky of the Hush Music Foundation which produces recordings of therapeutic music for use at the Royal Children's Hospital in Melbourne.1st prize in the 2001 Symphony Australia Young Conductor of the Year Competition.
The 2001 Nelly Apt Scholarship.
The 2003 Brian Stacey Memorial Trust Award, presented at the Helpmann Awards ceremony in Sydney.
The 2007 Limelight magazine's Best Newcomer Award.
The 2010 tri-annual Melbourne Prize Outstanding Musician Award (other nominees were Anna Goldsworthy, Slava and Leonard Grigoryan and Zulya Kamalova).