Zschech started on television at the age of 10, as part of an Australian children's show, Happy Go Round. When she was 13, her parents divorced and the emotional stress of being on television and her parents' divorce resulted in her having bulimia for about four years.
In 1980, when Zschech was 15, her father rededicated his life to Christ and began taking her to church, where she also became a committed Christian and met her future husband, Mark Zschech. When they married, her husband suggested that they move from Brisbane to Sydney, which was confirmed at a small church they were visiting one Sunday when the guest speaker said in the middle of his sermon, "This doesn't happen to me very often, but whatever it is you two prayed last night, God says do it now." They began attending Hills Christian Life Centre, which would become Hillsong Church.
Zschech sang jingles for a number of international companies including McDonald's, KFC and Coca-Cola, until she eventually joined the staff of Hillsong Church after penning "Shout to the Lord". She released a vinyl album in 1987 called "Make the Choice" and a cassette album in 1993 called Pearls & Gold.
Zschech and her husband have three daughters, Amy, Chloe and Zoe. In 2000 she had a miscarriage after 12 weeks.
Shout to the Lord was nominated as Album of the Year for the 1997 Dove Awards and was nominated as Song of the Year for the 1998 Dove Awards. In 2000, Zschech received a Dove Award nomination for Songwriter of the Year and received the International Award for influence in praise and worship.
In 2003, Zschech released her first official solo album, Kiss of Heaven. Change Your World followed in 2005. She has since released two albums, in 2011, called Simply Darlene and You Are Love. In addition to writing songs, she has written five books: Worship (1996), Extravagant Worship (2002), The Kiss of Heaven (2003), The Great Generational Transition (2009) and Revealing Jesus: A 365-Day Devotional (2013).
On 11 December 2013, Zschech was diagnosed with breast cancer. In a blog dated 30 November 2014, she wrote that she has been healed of cancer, which her doctor termed "quite miraculous".
Zschech was the worship pastor of Hillsong Church from 1996 to 2007, during which time she served as producer, vocal producer or executive producer for more than 20 albums under the Hillsong Music label and wrote more than 80 published worship songs. Under Zschech's leadership, the album People Just Like Us (1994) was the first Christian album in Australia to go Gold as well as the first to go Platinum and the album For All You've Done (2004) debuted at #1 on the Australian Record Industry Association album charts. Zschech explained Hillsong Music's stance in her book Extravagant Worship in a prayer: "Father, let them quickly get their eyes off of us. We just want to point them to you, God, because you are the Author of truth. You are the only One who is to be praised."
Zschech stepped down as worship pastor in 2007, but continued to write songs for Hillsong and to serve as senior worship leader on their live albums. Reuben Morgan was appointed Hillsong worship pastor in 2008.
In January 2011, Zschech and her husband, Mark, became senior pastors at Church Unlimited, later renamed Hope Unlimited Church, in Charmhaven on the Central Coast.HopeUC hosts an annual relationships conference, "The Living Room", that focuses on all aspects of relationships.
In April 2004, the Zschech family visited Rwanda, Africa and were inspired to launch "Hope Rwanda: 100 Days of Hope", a faith-based global initiative that provided hygiene options and education for the citizens of Rwanda, which eventually morphed into Hope Global. According to the official website, Hope Global currently exists to "offer practical solutions to countries devastated by war, genocide, and poverty." It has major centres in Rwanda, Uganda, Kenya, and Cambodia, runs long-term development projects, such as Hope Education and the Village of Hope, and has hosted Parramatta Eels trips to Rwanda with CEO Paul Osborne.
Zschech composed "Shout to the Lord" in 1993 and it has become one of the most well-known modern worship songs, being sung by an estimated 25-30 million churchgoers every Sunday since the song's release. She wrote the song during a time of personal struggle. When she presented it to Hillsong's then-worship pastor, Geoff Bullock, she was so embarrassed that she requested he face away from her as she played and sang.
"Shout to the Lord" was first recorded on People Just Like Us and has appeared on more than 200 different albums by numerous artists in multiple languages. It is also the title track for the first live album co-produced with Integrity Music featuring Zschech as a worship leader. It was Integrity Music's first album to feature a female worship leader. The album was nominated for the 1997 Dove Awards "Praise & Worship Album of the Year" at the Gospel Music Awards. The song was nominated in the 1998 Dove Awards "Song of the Year" category. It has been performed for the Pope at the Vatican and for the President of the United States.
On the global impact of "Shout to the Lord", Zschech said, "I can't take any credit for its impact. God decided to put his blessing on this song."
first Hillsong Live album as Worship Pastor; wrote "God Is in the House" with Russell Fragar, "And That My Soul Knows Very Well" with Fragar, "Let the Peace of God Reign", "Walking in the Light", and "I Will Run To You"
wrote "More to See" with Mia Fieldes, Deborah Ezzy (Zschech's sister), Donia Makadonez & Nigel Hendroff, "I Believe", and "At the Cross" with Reuben Morgan; The song "Mighty to Save" written by Ben Fielding and Reuben Morgan received the 2009 Dove Awards 'Worship Song of the Year' at the Gospel Music Awards
wrote "The Only Name", "Saviour" (which was previously recorded live on the album God He Reigns'), "Oh the Blood", and "Worthy is the Lamb" (which was previously recorded live on You Are My World and Unified Praise)
Supernatural (Hillsong Kids/Hillsong Music Australia)
wrote "I Will Sing" with Gio Galanti and daughters Chloe Zschech and Zoe Zschech