The photos, obtained by Fairfax Media, show Ms Bishop using her phone behind the wheel of her campaign car on Thursday afternoon.
The penalty for texting while driving is $400 and the loss of three demerit points in Western Australia.
"Everyone should comply with the law and I will ensure this does not happen again," she said in a statement to Fairfax.
The man who took the photo told Fairfax he saw her using the phone for about two minutes during slow-moving traffic stuck at a set of lights.
"I thought it was funny to see a Toyota Yaris with Julie Bishop's face on the side. Then it was even funnier when I realised it was actually Julie Bishop driving the Julie Bishop car," he said.
"Then it wasn't so funny when I realised she was using her phone as she drove. It was clear that she was holding the phone and using her thumb to swipe. I don't know if she was texting or checking Facebook or something."
Last year, Opposition Leader Bill Shorten reported himself to police after being filmed texting in a 40km/hr zone.
"Then it wasn't so funny when I realised she was using her phone as she drove. It was clear that she was holding the phone and using her thumb to swipe. I don't know if she was texting or checking Facebook or something."
