The Turkey international has joined on a season-long loan from Manchester United, with an option to make the move permanent for around £3.5 million, ending a frustrating three-year spell at Old Trafford in which he made just 17 appearances since arriving from Fenerbahçe for £4.3 million in 2023.
Celta Vigo football director Marco Garcés welcomed the deal.
"I'd like to thank him for his effort and willingness to negotiate, and Manchester United, who did a lot to make this happen. He helps us a great deal in increasing competitiveness in a specific position and being more competitive on the pitch now that we have to face three competitions," Garcés said.
Bayindir said he had already felt at home among his new team-mates before even completing pre-season training in Italy.
"After signing I went straight to Italy and it felt like I already knew a lot of the lads.
"Everything is new for me. My team-mates were lovely, they helped me so much, they asked me at every moment if I needed anything and I felt very welcomed from the start," he said.
He credited head coach Claudio Giráldez's personal involvement with sealing his decision to move to Galicia.
"I obviously had other options before coming here, but I already knew the club's history, and once I could speak with Claudio, coming here became my only option. I spoke with my agents and I wanted to come here and give my life for the club," Bayindir said.
The 28-year-old will compete directly with Ionuț Radu for the number one shirt, a rivalry he says has started on good terms.
"When you arrive at a club as a goalkeeper it's normal for it to feel like a strange situation, but Radu in particular was very good with me from the start. He helped me at every moment and we have a very good relationship. Obviously now we have to compete for a place and we'll both be giving our best out on the pitch. Competition is good for the club and we're both going to give our best," he said.
Learning Spanish and adapting to LaLiga's style are now priorities, Bayindir added, along with the chance to play European football again after Celta secured Europa League qualification last season.
"I always like to give my best and be the best goalkeeper I can be. For that it's very important right now to learn Spanish. I've already started classes to understand my team-mates and express myself well. LaLiga and its style of play are very important for a goalkeeper.
"You have to understand it, know what the coach is asking for and do whatever is most effective in each moment. Playing in the Europa League mattered in my decision to come here. It's difficult to be a second-choice goalkeeper, but I'm someone who always likes to push myself, though in a team you can't only think about your own position, and you have to help the team as much as possible, and to do that you have to do your job as well as you can."