Richard Leaman, chief executive of Guide Dogs, will step down at the end of the month.
A spokeswoman for Guide Dogs said Leaman had agreed with the trustees that it was the right time to step down and he was "taking some time to consider his options for the future" before sharing any plans for what he would do next.
Leaman said in a statement he would be sad to leave the charity, which more than doubled its annual income during his tenure to £103.7m in 2015.
"I have had six remarkable years leading Guide Dogs and I am exceptionally proud of the charity’s achievements during that time," said Leaman, who was a rear admiral in the Royal Navy before joining the charity.
"I am particularly proud that Guide Dogs has gone from strength to strength and is now extremely well positioned to continue to grow in the future."
Jamie Hambro, chair of Guide Dogs, said the charity’s trustees were "immensely grateful for Richard’s outstanding work".
Steve Vaid, deputy chief executive of Guide Dogs, will be acting chief executive while a permanent successor for Leaman is sought.