"I have made peace with myself about this decision long ago and I believe it's the right time to retire," he told the 'Afrikaans' from Mirpur, but conceded that he was coming into his own as a captain only now.
"It was an exciting period with various highs and lows and I had to grow up very quickly."
At 22, Smith became the youngest captain in South African cricket history when he took over from Shaun Pollock in 2003. Pollock had refused a call from Cricket South Africa (CSA) to step down, after which the body dismissed him from the post.
"At such a young age it would certainly always be a roller-coaster ride. I only started really being in control in the past four years," Smith said.
"Now for the first time I feel that I know what it is about and that I can truly call the team 'mine'. Although leading the team was a "tremendous challenge" owing to political interventions in team selections and "buckets full" of criticism of his leadership style, there were also many highlights, Smith added.
"The success that we achieved in 2008 in England and Australia was unforgettable. And seeing how the players that (former coach) Mickey (Arthur) identified earlier are now staking their claims is particularly gratifying," he said.
Smith, who has already handed over the captaincy of the T20 side to Johan Botha, will however, continue to lead the Test squad for the time being.
"(This World Cup) is a very important tournament for me for more than one reason," Smith said after the Proteas beat Bangladesh at the venue where he made his debut as captain. Since then, he has led the team in 146 internationals, the most by a South African.
"It's disappointing that I have not made a big batting contribution yet, but hopefully, I can get it right when the team needs it the most, and I can say goodbye to them in a fitting way."
Smith will not review retirement decision
Advertisement