Wednesday's Principality Stadium concert, in front of about 60,000 fans, kicks off the UK leg of her Renaissance tour.
People are expected to travel from around the UK and as far away as the United States, Lebanon and Australia.
Cardiff council is warning concert-goers to plan their journey in advance and arrive early.
"I'm so thankful that this opportunity has come, that I finally get to see her," said George Crocker, 15, from Avoca Beach, New South Wales, Australia.
"She is a goddess, she's my mother. She is my absolute queen... she's just everything in a person.
"Everything about her is just perfect."
A fan since the age of four, he has travelled with his mum Penny, and added: "I'm just going to bawl my eyes out the whole time, I just know that for a fact."
The Renaissance World Tour is 41-year-old Beyoncé's first solo tour in seven years, and many fans have travelled a long way to see her in Cardiff.
Giovani Tana, 20, arrived in the Welsh capital on Saturday, after flying to London from Beirut and catching a train.
"It's my first time in the UK ever, so it's a great excuse to come," he said.
"I think London is fully sold out and I thought I would explore a different city."
He is looking forward to connecting with other fans, adding: "Her work is incredible. No-one puts on a show like she does.
"I respect her work and what she's doing for the queer community is truly incredible.
"For her to be on that stage representing a lot of different people is inspirational."
It is not the singer's first time in Cardiff - she joined husband Jay-Z on the On The Run II Tour in the city in 2018.
The show, which kicks off at 19:00 BST at Cardiff's Principality stadium and will end at 22:30 BST, follows appearances in Stockholm, Sweden, and Brussels, Belgium, in a tour that will end in the United States in September.
The tour setlist includes 40 hits spanning Beyoncé's career as well as singles from the album Renaissance released in 2022, including Break My Soul and Cuff it.
Over the next three weeks the singer will also play at venues in Edinburgh, Sunderland and London.
Cardiff council has warned roads into the city will be "very busy".
It has strongly advised people to plan their journey in advance and arrive at the stadium early.
An Ed Sheeran concert in May 2022 saw 15-mile queues from the Prince of Wales Bridge towards Cardiff on the M4, causing some people to miss the event.
By road
There will be a full city centre road closure from 16:00 until midnight.
Those attending are advised to use a park ride facility at Leckwith Stadium, or park and walk spaces at County Hall in Cardiff Bay.
Train
Trains are expected to be very busy after the event and a queuing system will be in place at Cardiff Central station.
Great Western Railway are running extra services to Swansea, Newport, Bristol and Swindon afterwards.
Passengers are being advised to check the GWR website before travelling as industrial action on 17 May is likely to cause "some short-notice changes and cancellations", the operator said.
Over-running South Wales Metro engineering works also mean there will be no trains north of Pontypridd on the core valley lines of Treherbert, Merthyr Tydfil and Aberdare.
Gates open to the public at 17:00, while the box office will open at 13:00.
Officials say all tickets have been issued digitally and should be downloaded and transferred through the relevant app before arriving at the stadium.
People are also being warned not to screenshot tickets as this could invalidate them.