In 1842 the Rev. Alfred Holmead was brought to Ellicott's Mills to serve as chaplain of Patapsco Female Institute by its principal Almira Phelps, and Holmead used the opportunity to begin a new Episcopal parish in the village. It was initially called "Grace Church," but changed its name to St. Peter's in 1848 to avoid confusion with the parish in Elk Ridge. By 1845 a church had been built on the bluff behind St. Paul's Catholic Church, facing the river and the new railroad. In 1873 a parish rectory was built next to the church.

The parish initially struggled, and parish clergy had to supplement their income by teaching or by serving as the institute chaplain (which they did off and on until 1872). The parish grew, and by 1892—its 50th year—had 100 communicants; it became the parish of village shopkeepers and merchants, mill foremen, and some professional folk. By the 1860s St. Peter's had begun to use more intentional or more traditional liturgical styles, which in time came to be described as "Anglo—Catholic," and those traditions continue in the parish.

In 1927 Julius Velasco took charge of the parish, and remained as clergy in charge or as rector until 1945, watershed years for St. Peter's. The coming of the automobile made the hillside next to St. Paul's quite congested, and the parish looked for a new location. Then on Saturday afternoon, October 14, 1939, the old church burned to the ground. The parish took the modest insurance proceeds and built a new church at the intersection of Rogers Avenue and Frederick Road, a "suburban" location halfway between the old site and St. John's Church. The new church was placed in use in June 1940; the new structure included a small apartment for the residence of rector and his family. The new building reflected Fr. Velasco's pronounced Anglo—Catholic bent, with a sanctuary lamp, tabernacle, stations of the cross, votive candles, side altars, and so forth.

St. Peter's fell on hard times, and after 1948 was unable to support a clergyman; the parish was cared for until 1964 by members of the Society of St. John the Evangelist (the Cowley Fathers), while they served as chaplain of All Saints Convent in Catonsville. Many in our community recall with great affection Fr. Earle Maddux SSJE, who served at St. Peter's—while serving as convent chaplain—from 1951 until 1964. Under Fr. Maddux' guidance, and the faithful stewardship of the Guild of St. Mary's, which held innumerable dinners, card parties, and rummage sales, funds were raised to pay off parish indebtedness, and the new church was consecrated on May 26, 1956.

St. Peter's called its first modern—era rector in 1964, Fr. Raymond Atlee, and entered into a period of sustained growth. In 1968 a new rectory was built, and in 1978 a parish hall and educational wing was added to the church, In 1980 the parish sponsored the founding of a parochial mission, St. Andrew's in Glenwood.

In 1992 St. Peter's observed its 150th anniversary and published a parish history. In December 1994 its most recent rector Kirk Kubicek arrived, and the parish has now embarked on a time of renewed growth.