Mill Valley Road and the side-roads off it are a 21st century development. Like many roads in this area, it gets its name from the fact that Ligoniel was a mill village. There was a beetling mill nearby at the confluence of the Ligoniel River and the Forth River. Later, in 1857-59 a flax spinning mill was built by John Emerson a little further north and upstream (which became the Ballysillan Flax Spinning Mill), and there was also a weaving factory.
The Irish form of the name was approved in September 2023.