Nigeria central defender Efe Ambrose has signed a three-year contract with Celtic after an undisclosed fee was agreed with Israeli club Ashdod.
The 23-year-old, capped 14 times by his country, has spent the last two seasons in Israel's top flight.
Ambrose said: "It has been a long day, but it has been worth it.
"Today is one of the happiest days of my life, signing for one of the biggest clubs in the world - a club I have known about since I was young."
Celtic manager Neil Lennon had been looking for cover in central defence after the departures of Glenn Loovens and Daniel Majstorovic.
And he has secured Ambrose, who can also play at right back and in central midfield, after the Nigerian jetted into Glasgow earlier in the day to undergo his medical at Ross Hall.
"I am the kind of player who plays where it is of benefit to the team," he told Celtic's website.
"If the manager trusts me to play in midfield or defence then I trust him and I am the kind of player who will give 100 per cent, whatever the coach asks of me."
Ambrose, who is an Olympic silver medallist, began his career with Kaduna United in his homeland and thanks Ashdod for giving him the opportunity to play abroad.
"The move to Israel really opened the door for me and gave me my opportunity," he said.
"I had been to other clubs, but they were the ones who gave me my chance."
Now Ambrose was looking forward to playing in the Champions League groups stage.
"I have come here to find we are in the same group as Barcelona, Benfica and Spartak Moscow," he added.
"It's a lovely group, you might call it the group of death and it will be hard, but hard work always pays."
As Ambrose arrived at Celtic Park, fellow defender Andre Blackman left the Scottish champions on loan to Inverness Caledonian Thistle.