"It has been a great privilege to represent the Bay of Plenty in Parliament for the past 20 years," he said. "As an MP there's an innumerable number of individuals that you help."
Mr Ryall earned a business degree and spent a couple of years working in a bank before entering Parliament in 1990.
He added to his business background through two stints as Minister of State Owned Enterprises which he said was a key highlight.
But Mr Ryall said he felt he had achieved some good for the region with his dual role as Minister of Health.
"I'm pretty pleased with the number of investments in Tauranga Hospital and Whakatane Hospital and the Eastern Link now we're about to get it up and running," he said.
"The other thing I'm very pleased about is the Government decision to fund Herceptin for women with breast cancer. The health system is on par with Fonterra in that it employs 75,000 people. To have the opportunity to lead that is something that you don't get very often."
Mr Ryall said he looked forward to celebrating his appointment with family members when the news was announced. "I imagine I will have my parents and in-laws giving me a ring on the day it's published," Mr Ryall said.
"We will probably have a quiet celebration with family members in Ohope."
Mr Ryall will begin work with Auckland law firm Simpson Grierson at the end of January.