According to the Soweto giants, Mahlasela has penned a two-and-a-half-year deal with an option to renew for another year.
The 26-year-old expressed his delight soon after he was unveiled by Chiefs on Wednesday afternoon.
He had long been linked with a possible move to Amakhosi, and indications were already there that he would end up at Naturena after rejecting a new Celtic offer towards the end of 2016.
As Goal reported last week, Celtic had threatened to put the deal on hold if their asking price for Mahlasela wasn't met.
However, Chiefs returned with a better offer and sweetened the deal by including Gordinho.
While the majority of Amakhosi fans would be disappointed with the departure of Gordinho to Phunya Sele Sele, it is worth noting that the centre-back was no longer a regular under Steve Komphela.
He had not featured for the Glamour Boys since October 31 against Polokwane City.
The return to full fitness of Teenage Hadebe coupled with a rib injury he suffered in September saw him make a mere seven appearances for the club in all competitions since the start of the 2017/18.
Chiefs took to their social media platforms to announce the deal.
Mahlasela Signs!— Kaizer Chiefs (@KaizerChiefs) January 3, 2018
Kaizer Chiefs would like to confirm the signing of attacking midfielder Kabelo Mahlasela from Bloemfontein Celtic on a 2 and a half year deal with a one year option.
“I’m grateful to be here. I believe I can grow and also help the team.”- Mahlasela#KCOneTeam pic.twitter.com/lapMfj99y2
Gordinho loaned to Celtic— Kaizer Chiefs (@KaizerChiefs) January 3, 2018
Kaizer Chiefs would like to confirm that defender Lorenzo Gordinho has been loaned to Bloemfontein Celtic on a one-year deal.
We wish him all the best during this tenure.#KCOneTeam pic.twitter.com/NH0IKZ31bY