Barnsley will be relegated if they lose and Norwich win at Charlton but Barker is professional enough to know he must do his best for his current employer.
"It's true I've got a lot to thank Barnsley Football Club for as it was them who started me out on my career," said Barker, who joined Argyle in August from Queens Park Rangers.
"But, if I'm selected to play on Sunday, I won't have mixed emotions. I'll be going out there to help Argyle win.
"Obviously, I'm hoping that Barnsley will stay up, but I also want Argyle to get a home victory - there have been too few of those this season.
"My main concern is that Argyle do well, both on Sunday, and for next season."
Barker laft Oakwell in a £600,000 move to Cardiff City in 2002.