The 18-year-old forward, whose dad won the Ballon d'Or in 1995, netted twice in six first-team appearances for Ligue 1 side PSG.
Following the sale of striker Moussa Dembele in the summer for £19 million to Lyon and the club's failure to secure a replacement, the off-field issues surrounding Leigh Griffiths - who has been given an extended period of leave - has stretched Celtic thin up front and the capture of Weah and Bayo will certainly boost competition as well as the attacking threat at the club.
"I just want to kick on now and get as many games as I can under my belt and show what I'm capable of", he said.
Son of 1995 Ballon d'Or victor and Liberian president George Weah, the 18-year-old has scored two goals in three appearances for PSG this season but saw his opportunities limited by a star front three of Neymar, Kylian Mbappe and Edinson Cavani. It's all in the package - great team, great supporters, great stadium, great coaching staff, so it's a great place to come and learn.
Man charged over escape room fire deaths in Poland
The girls had gathered for a birthday celebration in Koszalin, in northern Poland, on Friday when a blaze erupted at the house. Kosiec said the bodies were found after firefighters put out a fire that broke out around 5pm at the location.
'Can't wait to get started and get the chance to play in front of those fantastic fans I've heard so much about.
"I went there knowing I had to put the work in to get where I wanted to be", Weah told BBC Scotland.
He said he would hold talks with the 28-year-old when he returns to Glasgow at the weekend, pointing out that the player was "not on holiday". I think it will go right down to its very end. It's great to see him again and how he has progressed and seeing his development at this club.
The eight-times capped United States global signed on Monday for the rest of the season and joined his new team-mates at their training camp in Dubai. "He's hungry too", Celtic manager Brendan Rodgers told the club's website.
The Hoops have already been very busy in January, bringing in three players so far.