There are 3 books by Kiera O'Brien on BookOrb. A strong starting point is Millie vs the machines (2015). The bibliography below is in publication order, with series grouped in reading order.
Standalone books
Frequently asked questions
How many books has Kiera O'Brien written?
BookOrb lists 3 books by Kiera O'Brien.
Where should I start with Kiera O'Brien?
A good starting point is Millie vs the machines (2015).
What is the Kiera O'Brien books in order list?
In publication order: 1. Millie vs the machines (2015), 2. Millie Vs the World (2016), 3. Millie Vs the World (Millie Vs the Machines) (2016).