Smith, the Rugby World Cup winning All Blacks assistant coach, looked after Maitland as part of the New Zealand Under-19 and Under-20 World Cup-winning Colts sides.
Smith, a hugely respected backs coach who knocked back England head coach Stuart Lancaster's pursuit of his services to stay with SuperRugby side The Chiefs, said New Zealand were rocked when the 24-year-old left his homeland.
Since making his Super Rugby debut in 2008, Maitland has scored 24 tries.
He equalled the record for the most individual touchdowns in a tournament game when he crossed the whitewash four times against the Brumbies in 2011.
Smith has backed Scotland-qualified Maitland to be a high scorer for Glasgow when he arrives next month.
The All Blacks coaching legend said: "I would say this is a massive coup for Glasgow and Scotland.
"Sean is the quickest player in New Zealand Rugby right now and they are disappointed to lose him.
"I have no doubt that, if he settles well, he will light up the PRO12 and score a barrel-load of tries for Glasgow.
"He is a big lad at 6ft 3ins, is physical and versatile, in that he can play on either wing or at full-back.
"He has an excellent skill set and is an out and out try scorer.
"Like I say, this is a massive coup for Scottish rugby and I have no doubt Sean has everything in his locker to become a household name over here."
Smith added: "I have coached Sean intermittently through his development and he is a top lad.
"I have no doubt he will fit in really well at the Warriors.
"He will also add some more competition for places and the importance of that in a squad can never be underestimated."
With Warriors current backline decimated by injury, Maitland's arrival can't come quick enough.
It is understood that with Glasgow being able to make two changes to the Heineken Cup squad, they have already named, Maitland will be able to take his place in the Glasgow back line for the must win visit of Castres, to Scotstoun, on December 7.
Glasgow head coach Gregor Townsend is delighted to land a player of Maitland's calibre. He said: "Sean's try-scoring record in Super Rugby speaks for itself.
"He will be a fantastic addition to our squad and it's another indication of the increasing profile of Glasgow that a player of his ability and ambition sees us as a club where he can continue to progress."