The Germany international will be remaining with the Royal Blues until 2017 with the announcement coming at the end of a successful day for the club, who beat local rivals Borussia Dortmund 2-1 to move up to fourth in the Bundesliga.
"We were quick in reaching an agreement, that I wanted to stay here," he said.
"I had always stressed that I am extremely happy here at Schalke. The club also made it clear that they wanted to keep me, so that is why we reached an agreement.
"I am looking forward to being able to play football for Schalke for another four years.
"This is my home and my true love."
Howedes said the second 2-1 win over Dortmund this season was "pure relief" after a tough second-half with the visitors pushing for an equaliser.
"We were under a bit of pressure in the second half, but I think given the number of counter-attacks we had, in the end, the win is totally deserved," he told Sky television.
"We played a great first half, put Dortmund under pressure the whole time and created numerous chances, totally deserving our 2-0 lead at the break."
A knee injury to Klaas Jan Huntelaar dampened the Schalke spirits, though.
The Dutchman tore knee ligaments and has been ruled out for several weeks, meaning he will miss the decisive Champions League tie with Galatasaray on Tuesday.