The club director noted Baggott's age, drive, and defensive profile align with Millwall's tactical requirements.
"He's a good age, has a real appetite to improve and fits the profile we look for defensively," said Gallen.
Gallen pointed out that the acquisition strengthens a key area of the squad that has consistently performed well.
"Elkan comes in to bolster our defensive options in an area that has been a real strength for us in recent seasons and we're confident he'll add real competition and quality to that group," he said.
The club confirmed Baggott's arrival as they look ahead to his integration into the squad for the upcoming campaign.
"We're pleased he's chosen to join and we're looking forward to seeing him progress here," said Gallen.
