The Rot & Ruin series by Jonathan Maberry is a zombie apocalypse trilogy, and the order of the books is:
1. Rot & Ruin (2009)
2. Rot & Rule (2010)
3. Rot & Rise (2011)
There is also a prequel novella, Rot & Regret, which takes place before the events of the first book. You can read it either before or after the main series.