The 19-year-old has penned a three-and-a-half year deal with the Barclays Premier League club and will link up with Swansea's under-21 squad.
Glasgow-born Blair made 10 appearances for Ladbrokes Scottish Championship side Falkirk after breaking through last season and joins former Bairns Botti Biabi, Stephen Kingsley and Jay Fulton at the Liberty Stadium
Blair becomes the first Swansea signing since Francesco Guidolin was appointed as head coach last week
"It feels great
I never thought I would get the opportunity to join a Premier League club," Blair told the official Swansea website
"I want to kick on now and get myself some game time between now and the end of the season.
"I played with Stephen, Jay and and Botti at Falkirk
The three being here will help me settle quicker."
Source : PA
Source: PA