Born in Glencull, near Ballygawley, County Tyrone, Northern Ireland, Harte was educated at the Christian BrothersGrammar School in Omagh. He trained to be a teacher at St. Joseph's College in Belfast. He taught for five years at De La SalleBoys School in Kircubben. He then moved to St Ciaran's in Ballygawley. In his 22 years spent there, he achieved numerous successes, including Tyrone, Ulster and All-Ireland Vocational Schools titles. He continued working there as he progressed through the county ranks of Tyrone's Gaelic football side, bringing them to a National Football League title, All-Ireland Minor and U21 victories and eventually, in 2003, the Sam Maguire Cup.
Management
Raised in Ballymacilroy outside Ballygawley, County Tyrone, Harte managed Tyrone Minors and under-21s and won the All-Ireland with both these teams before he was named the Tyrone Senior Football Manager. He guided the under-21 team to two All-Ireland Under 21 titles and three Ulster Under 21 titles. He led the Minors to an All-Ireland Minor title and three Ulster Minor titles. He subsequently managed his home club of Errigal Ciarán and was successful with this team as well, winning the Tyrone County Championship and Ulster Championship. In more recent times Ulster Championship success has not come easy for Harte's Tyrone, having been knocked out 4 times by Donegal in 2011, 2012, 2013 and 2015.
Advocacy
Harte has been very forthcoming with his Christian views. In 2009, he went to Derry to attend the launch of Patrick McCrystal's controversial book Who is at the Centre of Your Marriage, the Pill or Jesus Christ?. McCrystal's opinions have generated discontent, examples: "For too long, contraception promotion has gone virtually unchallenged. Contraception is the unspoken cause of too much marriage break-up" and "Chastity before marriage and fidelity after it is the only way to truly combat AIDS. The Pope is right. European condom imperialism is not the answer. The battle against contraception is not over so long as one married couple uses contraception." In 2010, as part of the Catholic Church's "Year for Priests" celebration, he contributed to a DVD, In Praise of Priests, featuring interviews with various people expressing admiration for their favourite priest. In February 2012 Harte defended the character of self-confessed rapist Ronan McCusker, on the basis that he "comes from a widely-known GAA family in Tyrone.” "Judge Piers Grant singled out the character reference from Harte as one of the "mitigating factors" which led him to pitch McCusker's sentence towards the bottom of the range; two-and-a-half years, 15 months in jail, 15 on licence." Harte supported the No Vote in the 2018 abortion referendum.
Writing
In 2009, Harte began writing a weekly column for the Northern Irish newspaper, The Irish News. To date his column has focused on hot topics in Gaelic games, referees and other GAA-related topics. In October 2009, Harte published an autobiography, Harte: Presence Is The Only Thing. It was published by Poolbeg.
Personal life
Harte is married with several children. His daughter Michaela McAreavey was murdered on her honeymoon in Mauritius in January 2011. He also lost two brothers around the time of his daughter's murder.