The 24-year-old smashed through her own Commonwealth record this evening with a time of 4:31.76, earning her the top prize, while England's Aimee Willmott scooped silver and Keryn McMaster of Australia won bronze.
"It's been a tough year," Miley told reporters. "I've had my scalp taken a couple of times and I had to really stop and re-evaluate - 'should I keep going, is this the right direction that I'm going in? Do I need to move?' I totally trust the support that my dad's done and I really wanted to take ownership of my sport and really do what I need to get done.
"The sacrifices I've made, my family I've made. It's been very, very tough on everybody, not just me, so for me I guess it's just years of a sigh of relief for my whole family. The fact that they were there - that meant the world to me to be able to hug everybody at the end."
Miley earned a Commonwealth gold in the same event four years ago in Delhi.