Former Germany international Frings, 34, and Koevermans, 32, have arrived at the Canadian side on free transfers, putting pen to paper on 'designated player' deals, meaning their contracts fall outside the constrictions of the club's salary cap.
Midfielder Frings, who has made 79 appearances for Germany, was released by Werder Bremen at the end of last season while Koevermans, a prolific striker in his homeland and capped four times by Holland, has been without a club since leaving PSV Eindhoven. Toronto's director of player development Paul Mariner hailed the double capture as a major coup for the club.
"From a development of players view point, to bring players in of the calibre of Torsten and Danny, it's going to be big for the young players," said Mariner. "They are going to have some unbelievable role models to look up to.
"I know that they are the right people, the right calibre of people, because contrary to popular belief, players like this don't grow on trees. I know there are a lot of players available now with contracts ending over in Europe, but you've got to sift through and go through the right character as well as the right abilities."
Toronto's coach, former Holland international Aron Winter, also welcomed the arrival of the new big-name signings. "This is a big day for us," Winter said. "In the system that I want to play, it's very important that each line has a leader."
Frings and Koevermans are not eligible to play for their new club until 15 July. Their MLS debuts are therefore likely to come against FC Dallas on 20 July.