Full-back Ryan, who joined the Championship side on loan on Friday, sent in a lofted ball from the right wing position which flew into the top corner five minutes before half-time in the Lions’ home match against Ipswich Town.
It proved to be the only goal of the game, giving Ian Holloway his first win as Millwall manager.
Elsewhere in the Championship on Saturday, Benoit Assou-Ekotto claimed an assist for Queens Parks Rangers’ winning goal as the R’s saw off Huddersfield Town 2-1.
Benoit’s corner was turned home by team-mate Charlie Austin 11 minutes from time to put the hosts in front for a second time in the game. Benoit played the full game, as did midfielder Tom Carroll.
Also celebrating a victory was defender Bongani Khumalo, who played 90 minutes in Doncaster Rovers’ 3-0 win against Wigan Athletic.
Jon Obika stepped off the bench for Brighton & Hove Albion with 11 minutes of their away fixture at Derby County remaining, but the forward was unable to prevent his side from slipping to a 1-0 defeat.
Alex Pritchard, Grant Hall and Ryan Mason were all in the Swindon Town side which lost 2-0 at Gillingham in League One, the latter duo being substituted in the second half, while Shaq Coulthirst maintained a watching brief from the bench as Leyton Orient went back to the top of the table with a 2-1 win at Crewe Alexandra.
In the Premier League, Jake Livermore played 90 minutes for Hull City in their 1-0 defeat at Norwich City while, in Spain, Yago Falque was an unused substitute for Rayo Vallecano in their 2-0 reverse at Elche. Cristian Ceballos was similarly inactive on the bench for FC Arouca, as they lost 2-1 to Sporting Lisbon in Portugal.