The former US president's wife, Laura Bush, drenched her husband with icy cold water, as he was sat writing a cheque to go towards the fundraising effort.
George was challenged by a number of stars, including his daughter, Jenna Bush Hager, to take on the challenge.
The cause aims to raise awareness for ALS (amyotrophic lateral sclerosis, or motor neurone disease), a terminal illness that weakens and stiffens muscles. The challenge involves people having a bucket of freezing water poured over them, while also nominating others to follow suit.
"To you all that challenged me, I do not think it's presidential for me to be splashed with ice water, so I'm simply going to write you a cheque," George said, before being soaked by his wife.
She added jokingly: "That cheque is for me. I wouldn't ruin my hairstyle."
After drying off, George challenged his predecessor in the White House, Bill Clinton, to follow his lead.
"Yesterday was Bill's birthday and my gift to Bill is a bucket of cold water," George said.
President Barack Obama has declined to take on the challenge, but will instead make a monetary contribution to the campaign.