The Gippsland region was first settled in the early 1840s and was initially served by priests on horseback from the Monaro region of NSW.
Sale was made a diocese on May 5, 1887, initially encompassing all the land to the east of the Bunyip River.
First Bishop was Irish-born James Francis Corbett, who had been parish priest at St. Kilda and Chancellor of the Archdiocese of Melbourne.
When he arrived in Sale on September 1, 1887, there were only four priests in the diocese, all of whom belonged to the archdiocese, no nuns, 16 churches and seven schools. Three of the priests chose to return to the Archdiocese.
Bishop Corbett set about rectifying the shortage of priests and religious by sailing for Europe in 1889. He returned a year later with five young Irish priests and seven French sisters of Our Lady of Sion.
While in Europe he also purchased church bells which were erected in a free-standing belfry in the cathedral grounds, statues of the Sacred Heart and Our Lady, Stations of the Cross and some well-chosen reproductions in oil of religious works by some of the Old Masters.
Under Bishop's Corbett's guidance the diocese continued to grow with a succession of parishes and schools being established across the region.
After Bishop Corbett died in 1912 at age 76, he was succeeded by Bishop Patrick Phelan who inherited a diocese with a Catholic population of 13,000, one sixth of whom lived in the cathedral parish and the rest scattered over 16,350 square miles (42,350 square km) of the province.
In 1913 he established the Sustenance Society for Sick and Inform Priests, which later became the Priests' Retirement Fund and more lately the Priests" Welfare Fund.
Bishop Phelan saw the need to provide quality secondary Catholic education for boys and so set about raising £25,000 over three years to build St Patrick's College in Sale. This boarding school opened in 1922 and has been operated by the Marist Brothers since then, although it is now part of the co-educational dual campus Catholic College Sale which also incorporates the former Our Lady of Sion Girls' School operated by the Sion Sisters.
When Bishop Phelan died in Ireland in 1925, the parish and college were both free of debt.
The third Bishop of Sale was Bishop Richard Ryan who saw the diocese through the Great Depression of the 1930s, World War 2 and perhaps, the greatest challenge in the massive post-war growth and influx of refugees and migrants from Europe.
When Bishop Ryan died in 1957, he was replaced by Bishop Patrick Lyons who oversaw a major change to the diocesan boundaries in 1959 with the inclusion of the parishes of Berwick, Cranbourne, Pakenham, Iona, Maryknoll, Koo Wee Rup, Dalyston and Korrumburra.
These areas were excised from the Melbourne Archdiocese and while they were mainly rural areas at the time, those closest to the archdiocese have undergone rapid growth and are now outer Melbourne suburbs.
Fifth Bishop of Sale was Bishop Arthur Fox, previously an auxiliary bishop in Melbourne, who took over in January 1968 and proved to be an accomplished administrator. He revamped the old Sustenance Society and renamed it the Priests' Retirement Fund which ensured that maintaining retired priests would not be a major financial burden on the diocese.
The initial planning for the setting up of the highly important Catholic Development Fund also took place during his time of office.
After his retirement in 1981, he was replaced by Bishop Eric D'Arcy who oversaw the first stage of modernising the cathedral, before being appointed Archbishop of Hobart in 1988. The Catholic Development Fund was established under his leadership in 1984.
Seventh Bishop, Bishop Jeremiah Coffey undertook a major extension to the cathedral in 1993 and has also been responsible for overhauling the diocese's finances, appointing a business manager, setting up a finance committee, council of priests, diocesan pastoral council, diocesan executive and pre-paid funeral fund.
In 1999 he established the Bishop's Family Foundation and began an appeal to raise a capital base for providing welfare and charitable support for families across the diocese. All funds donated are held by the foundation and it makes an annual disbursement from its investments. To date around $1.2 million has been provided for projects aiding families..
In 2001, Journeying Together was launched as a process to establish a pastoral plan for the diocese to guide its development over the next five years.
The eighth bishop, Bishop Christopher Prowse came to the diocese in June 2009 after previously having served seven years as an auxiliary bishop of Melbourne Archdiocese. In 2012 he consolidated all diocesan offices at Sion House, Warragul, the former Our Lady of Sion Sisters convent school which was already occupied by the diocese's education office. The Bishop's Office, Catholic Development Fund, business manager and Catholic Media Gippsland moved from Sale, while the pastoral office, Marriage Tribunal and youth offices relocated from Newborough. The Warragul premises underwent a major extension and renovation to enable the move to take place and diocesan offices in Sale were later sold.
Bishop Prowse also initiated a major refurbishment of St Mary's Cathedral which included a new kitchen and toilets, repairs to failing cement render inside and out, and repainting. Shortly before he was appointed Archbishop of Canberra and Goulburn in November 2013, he renamed Bishop's Family Foundation as Trinity Families.
The ninth bishop, Bishop Patrick O'Regan was ordained at Catholic College Sale's St Patrick's campus on February 26, 2015.