Both were signed for one-year stints at the club and were registered in plenty of time to be eligible for this weekend’s trip to Birmingham City, The Star understands.
Striker Marriott, who signed a one-year contract extension at his parent club before completing his Owls deal, can be recalled by Derby in January and arrives having scored one goal in his four league appearances for the struggling Rams this season.
The 26-year-old emerged as a late target for Wednesday in a position Owls boss Garry Monk made clear throughout the window he wanted to strengthen. He is the fourth striker to sign for the club in a manic window that also saw Josh Windass, Elias Kachunga and Callum Paterson join Jordan Rhodes as options up top.
Flint, a name well known to those behind the scenes at Wednesday having been a target during Carlos Carvalhal’s tenure, is a six-foot-six centre-half with a strong reputation in the Championship as a powerful, goal scoring defender.
The signing represents quite a coup for Wednesday and comes just over a year since Flint signed for Cardiff in a deal believed to be worth somewhere in the region of £7m.
He too joins fierce competition for places in his position, though arrives at an opportune time with the likes of Dominic Iorfa, Tom Lees and Liam Shaw having suffered injuries.
Flint was the new-look Owls’ ninth signing of the window, with Fisayo Dele-Bashiru, Izzy Brown, Chey Dunkley and youngster Korede Adedoyin having already completed deals earlier in the window.
Both players are understood to have been the club’s primary targets in the positions heading into deadline day.
A drawn-out attempt to sign West Brom forward Kenneth Zohore proved too expensive for Wednesday’s pallet as he joined Millwall, while other reported targets – young defenders Dion Sanderson and Jake Clarke-Salter – signed on temporary deals at Sunderland and Birmingham respectively.
The club also held off on reported interest in captain Barry Bannan and key man Iorfa in what was a transfer window well received by Wednesday supporters.