Sprint specialist Kittel, 31, split with his Katusha-Alpecin team to take a break from cycling earlier this year, following a rapid decline in form since 2017.
Announcing his decision to retire for good, he said he had "lost all motivation to keep torturing myself on a bike."
One of the best sprinters in the world at the He won five stages on the Tour as recently as 2017, yet his star has fallen since then, following an ill-fated move to Team Katusha-Alpecin in August of that year.
Kittel said he felt no trust at the Swiss-based team, "there was only pressure, pressure, pressure" and parted with Katusha-Alpecin by mutual consent earlier this year, intending to take a temporary break from cycling.
Since then, he said he has come to realise the negative effect cycling had on his life, and decided to give it up for good.
"The sport and the world you live in are defined by pain," he added.
"You don't have time for family and friends, and then there's the perpetual tiredness and routine.
"As a cyclist, you are on the road for 200 days of the year. I didn't want to watch my son grow up via Skype."