Wissa, 28, had been reportedly considering refusing to return to Brentford in an attempt to force a move to Newcastle.
However, the striker has now put the speculation behind him and is training with his teammates ahead of the 2025-26 season.
Newcastle had been heavily linked with a move for Wissa, but Brentford's £40 million asking price had been a major obstacle to a potential transfer.
The Magpies have since shifted their attention to RB Leipzig's Benjamin Sesko, but face competition from Manchester United for his signature.
