In a written statement posted on his Twitter account yesterday, McGrath issued a public apology.
"In 2008 I participated in a hunting safari in Zimbabwe that was licensed and legal but in hindsight highly inappropriate," he wrote.
"It was an extremely difficult time in my life and looking back I deeply regret being involved."
McGrath's wife Jane McGrath died of breast cancer in 2008 aged 42.
Before her death they set up the McGrath Foundation, a breast cancer support and education charity which to-date has raised more than $12 million.
The photos brought McGrath a barrage of criticism online.
"I deeply regret donating money to the McGrath foundation in light of his actions. Won't happen again," wrote Joshua Cullen.
"Yep, when a family member passed the only thing to make me feel better was killing endangered animals," Mark Simula wrote.
"Didn't look to upset with that gleaming smile," wrote Kerry Blades.
However, some came to McGrath's defence, including Ken Rowe who wrote: "you don't need to justify yourself mate, too many do gooders in this world".
On his Twitter account McGrath describes himself as a proud father, happy husband, retired cricketer, philanthropist and outdoorsman.
