Founded in 1853 with six members, St. Andrew's Episcopal Church, Seguin, is the oldest church in continuous mission in the Diocese of West Texas. Prior to the 1836 Texas Revolution certain forms of worship other than Roman Catholic were not accepted under imperial Spain and the Republic of  Mexico, which included this territory of Texas. Although American settlers, European immigrants, and native Indians had their own religious beliefs, there was no formal way to practice them.

The Episcopal Church in Texas got its formal start in 1850, when the Rev. Lucian Jones was sent out as a missionary to the Territory of Arkansas and Republic of Texas. Other missionaries followed him and one, Joseph Dunn, found his way to Seguin in 1853, where he found six communicants and a number of other persons desirous of services. He preached to large crowds on the evening of August 24th and 25th, and then organized a mission parish under the name Church of the Redeemer. There were other missions organized in Lockhart and Gonzales at about the same time, but each of these churches ceased operation for long periods of time while the Seguin church continued in its mission and ministry. Subsequent to its founding, the church changed its name to St. Andrew's because it was discovered that there was another Church of the Redeemer in Texas. This was not surprising since the Diocese of Texas at that time was larger than the country of France and communication was slow and difficult.

After the War Between the States, the Diocese of Texas was separated into three separate dioceses, and St. Andrew's became part of the Diocese of West Texas. This raw territory, which covered 110,000 square miles and contained only seven ministers and 427 communicants, became the See of a 34 year old former Confederate Army Officer just consecrated Bishop in Atlanta, Georgia. His name was Robert Woodward Barnwell Elliott. His headquarters was in San Antonio.

Under the leadership of Bishop Elliot, St. Andrew's grew and prospered in so far as churches in the frontier could prosper. After holding services for several years in an upper room on Court Street called Temperance Hall, lots were purchased at the present location, and a church was completed in 1876. It was designed by Stephen White, an architect who had worked on the Capitol of Texas and whom Governor John Ireland, a member of the parish, described as an artist. It was a wooden structure of excellent proportion. The church sanctuary was damaged by storms early in the 20th century, and has undergone additions and renovations through the years. These include a sacristy, a vestibule, and limestone setting on the outside. Nevertheless, the sanctuary stands today almost exactly as it was built in 1876. The structure has been used as the chapel for mid-week services, weddings, baptisms, and special occasions since 1986, when a new and larger church was built.

The people of St. Andrew's are faithfully proud of their history as the mission and the ministry of this parish approaches the 21st century. The St. Andrew's congregation celebrated a gala sesquicentennial in the year 2003.