Sandoval was spotted at the airport by local news station WHDH, whose sports director tweeted a photo of him from what appears to be baggage claim:
An executive with one major league club at last week's GM meetings in Phoenix said the Sox were making a big push to sign the 28-year-old Sandoval, who is also the top target of the San Francisco Giants, with whom he just won his third World Series title.
GM Ben Cherington would not confirm Sandoval's meeting with the Red Sox, but media reports indicated as early as last week that he was coming to town.
Cherington spoke in general terms of the value of a player visit.
"It's an opportunity for (players) to ask questions," he said. "These are choices, big decisions that free agents make. Obviously, a big piece of it is going to be the economics. But it's a life decision and they should get an opportunity to ask questions about whatever they want to ask questions about.
"It doesn't make sense in every case, but at times, you offer that and ask for it, just to give them a chance to ask questions."
A Giants source said he has "no clue" if Sandoval will choose to leave San Francisco.