The line was built in 1903–04[3] by the Pennsylvania Railroad (PRR) as a cutoff to avoid the busy Union Station and its yards.

In 1995, the Brilliant Branch (aside from the southernmost wye section) was leased and/or purchased by the fledgling Allegheny Valley Railroad (AVRR).

The segment south of the Brilliant Branch Railroad Bridge was used as AVRR's main link from the Pittsburgh Line to its Allegheny Subdivision along the south shore of the Allegheny River.

[5] The Brilliant Branch Bridge was subsequently repaired and was used by AVRR to access the AZCON scrap yard on the north side of the river.

[citation needed] In 2015, the AZCON scrap yard, the last remaining customer on the line, closed.