The 27-year-old, who has been capped twice for Scotland, left Tannadice for the Seasiders in the summer but failed to tie down a regular place for a team which has lost two managers already this season.
Hibs manager Pat Fenlon has been looking to strengthen his midfield this month and persuaded Blackpool to release Robertson, who has signed a two-and-a-half year deal with the Edinburgh club.
Robertson told HibernianTV: "I wasn't getting a chance at Blackpool and was wanting to play football again.
"Pat expressed an interest in bringing me here on a permanent basis and that was all right with Blackpool so the deal was rushed through.
"I was six months at Blackpool and only got one first-team game.
"After playing the whole season at Dundee United that wasn't great, so I'm looking forward to challenging for a first-team place."
The signing comes with Fenlon still trying to extend a loan deal for Honduras midfielder Jorge Claros, whose spell at Easter Road is due to end on Tuesday with his club Motagua still to make a decision on his future.
Fenlon said: "Scott will be a valuable addition to our squad - he is a skilful box-to-box midfielder, who is strong in the air and can provide goals.
"He is a player who has been on our radar for a while, so we were pleased to be able to get the deal over the line.
"Again, Scott has signed until the summer of 2015 which brings continuity and we believe he is the type of player our fans will enjoy watching perform."