Lawlor made 43 appearances for club and country in 2025-26 but was left out of Wales’ Nations League squad on Tuesday because of his injury.
The centre-back enjoyed a rapid rise to establish himself in the Bluebirds’ side under Barry-Murphy in League One and the boss is weighing up his role against Charlton.
“He’s trained really well. We’ll see how he is today and tomorrow, then make a decision based on who we feel is best to start this game,” said Barry-Murphy, whose side have drawn four and lost three of their seven league fixtures.
“But he’s fully fit, with no issues with his knee whatsoever, and he looks great.”
Lawlor’s reappearance and Fish’s impending return is good news for Cardiff, who have had to reshuffle their back line in order to deal with injuries.
In addition to the signing of Krystian Bielik from West Bromwich Albion, the Bluebirds have played full-backs Perry Ng and Joel Bagan in central positions in recent weeks.
With Gabriel Osho missing some games with his own injury, Barry-Murphy says Lawlor and Fish being back gives him much-needed selection choice.
“They’re two such outstanding players and to give us that extra depth to our squad that we’ve lacked in the earliest parts of the season is going to be really important,” he added.
“I’m very pleased to get them back and will try to build them up gradually to make sure that they stay fit, and both players can be very important for us.”
Cardiff are still without injured Wales internationals Rubin Colwill and Isaak Davies as well as defender Calum Chambers.
Chambers has knee, neck and back issues but Colwill and Davies are close to returns from their respective ankle and hamstring problems.
“We expect them to train in the middle of the international break, Rubin and Isaak,” said Barry-Murphy.
“Calum Chambers is having a further scan on his injury this afternoon, so we’ll know more on the timescale.”