Scotland midfielder Paul Hartley is delighted to have completed his £1.1m transfer from Hearts to Celtic.
Rangers failed with several bids for Hartley before the 30-year-old agreed a two-and-a-half-year contract, with the option for a further year.
"I'm over the moon," he told the Celtic website. "It's a dream come true for a boyhood Celtic supporter like me and I'm glad that I'm finally here.
"I've come here to win silverware and hopefully I can achieve that."
Hartley, capped six times by Scotland, will be reunited with his former Hearts team-mate, Steven Pressley, at Celtic.
"It makes it easier (knowing Pressley) but I'm still nervous, although I know a lot of the boys from playing with Scotland," added Hartley.
"It was a long day (the close of the transfer window) and hopefully I can enjoy my football now."
Hartley, who last year signed a new contract with Hearts, was omitted from head coach Valdas Ivanauskas' side that drew with Rangers at the weekend.
Ivanauskas said Hartley was left out due to "football business".
That was thought to have been a bid from Rangers, but it was second time lucky for Celtic after the Scottish champions failed to secure the player last January.
Hartley had two years of his contract to run.
But, in October, he appeared in public alongside goalkeeper Craig Gordon and former captain Pressley as the Scotland defender said there was "dressing-room unrest" at Tynecastle.
Pressley was released and moved on to Celtic, while Gordon and Hartley had to attend internal disciplinary hearings and had been surprisingly dropped from the starting line-up on a couple of occasions.
Rangers pipped Celtic on Tuesday to the signing of former Hibernian captain Kevin Thomson, but the roles were reversed in the case of Hartley.
Hartley is eligible to play in Celtic's Scottish Cup clash with Livingston on Sunday, having missed Hearts' involvement in this season's tournament due to suspension.
However, like Pressley, he is cup-tied for the club's Champions League adventures.