"We are lucky to have him as six or seven other clubs would've liked him to join them," the manager said of Thomas.
"But I have to thank Motherwell and, in particular, assistant James McFadden for letting the winger join Queens.
"Faddy and I were at Everton together and have stayed good friends. He thinks this is the right place for Dom."
Thomas, 20, has made seven first-team appearances this season for Well, but most of his 39 games for the Premiership side have been as a sub.
"Dom is a creative player who can play on either side or from in behind the strikers, he likes to turn and go, so I'm sure he will excite the fans," Naysmith told his club website.
"He's at the stage of his career where he needs to be playing every week."
Thomson, 19, has already made 18 appearances in the Championship this season, having spent the first half of the campaign on loan to Dumbarton.
"Both are versatile players and can play anywhere within the midfield, so it gives me more flexibility and will allow us to change formation when we need to," added Naysmith.
"Joe is a young player who I tried to get when I was at East Fife, but Celtic wanted him to play at a higher level, so he made the move to Dumbarton, where he has played all but two games for them in the Championship.
"Dumbarton are sorry to lose him, but both he and Celtic, where he is well thought of, felt that it would be better for him to play for a full-time club.
"He is good on the ball, is very energetic, likes to get between boxes and can really spot a pass. He likes to get involved with set pieces."
Gary Naysmith says his Everton connections helped Queen of the South sign Dom Thomas on loan from Motherwell along with Joe Thomson from Celtic.