The 19-year-old will be the fifth Fremantle player to debut this season if he plays on Saturday night and the third rookie, following Greg Broughton and Matt de Boer.
Pratt comes into the squad to replace the injured Ryan Crowley (foot) while defender Josh Head also travelled on Thursday morning.
Fremantle assistant coach Barry Mitchell confirmed the second-year rookie would be elevated ahead of the round seven clash with the Blues at Carrara Stadium.
"We're taking a couple of extras up, so we'll decide later today and announce the side later," Mitchell said from Perth before the side flew out.
Pratt beat all-comers for Swan Districts at the weekend and has been an effective and attacking defender in the WAFL this season.
Mitchell said the 183cm defender had a mature enough body to step into the AFL.
"He is [ready]," Mitchell said. "He's played really well in the backline for Swans. He's been really desperate (and) put his body on the line, so he deserves his chance to be in the squad.
"He puts himself in. He's not frightened at all. He plays with a really good intensity and that's what we need from all of our players."
With chief tagger Crowley likely to miss the next three months, Mitchell said Fremantle needed to find players capable of doing run-with jobs.
Carlton boasts a blue-chip midfield with Chris Judd leading Marc Murphy, Bryce Gibbs and Nick Stevens, but Mitchell said Fremantle had players in mind to cover the absence of Crowley and on-baller Rhys Palmer.
"We've got other players that can fit into that type of role," he said.
"Byron Schammer did a bit of it last week – he played on Daniel Kerr.
"Maybe we ask some other players to sacrifice their game a little bit and try and cut one out."
