The 33-year-old batsman was told that he was no longer in the England and Wales Cricket Board's plans after being dropped for the upcoming Caribbean tour and ICC World Twenty20.
Pietersen, who won The Ashes four times and has a Test batting average of 47.28, told the ECB's website: "Playing cricket for my country has been an honour. Every time I pulled on the England shirt was a moment of huge pride for me and that is something that will live with me forever.
"Although I am obviously very sad the incredible journey has come to an end, I'm also hugely proud of what we, as a team, have achieved over the past nine years.
"I feel extremely fortunate to have played at a time of great success for England cricket alongside some of the best cricketers the country has ever produced."
Pietersen was told of the unanimous decision to drop him and build for the future at a meeting with England Cricket's managing director Paul Downton this week.
"Clearly this was a tough decision because Kevin has been such an outstanding player for England as the fact that he is the country's leading run scorer in international cricket demonstrates," said Downton.
"However everyone was aware that there was a need to begin the long term planning after the Australia tour. Therefore we have decided the time is right to look to the future and start to rebuild not only the team but also team ethic and philosophy.
"England cricket owes a debt of gratitude to Kevin who has proved to be one of the most talented and exciting players to ever represent the country and his 13,797 runs are a testimony to his immense skill."
Pietersen's international career may be over, but he will still play for county side Surrey and feature in other tournaments such as the Indian Premier League.
"I believe I have a great deal still to give as a cricketer. I will continue to play but deeply regret that it won't be for England," he said.
Pietersen, England's leading run scorer in all formats, played 104 Test matches, 136 one-day internationals and 37 Twenty20 internationals for England in a career which began in November 2004.
Behind Sir Don Bradman, Pietersen has the second-highest run total from his first 25 Tests.