Galaxy S21 Ultra 5G • Locked AT&T

(38 reviews)

$298.00

Save $1,202.00

Free delivery by Jun 22 - 23

Express delivery by Jun 17 - 18 from $15.00

Restored professionally

Based on up to 100 points of inspection

Example image
Body
Visible signs of use
Verified parts
Battery for daily use
Example image
Screen
May have micro-scratches
Verified parts

Select the condition

All guaranteed 100% functional

Select the condition

Example image
Body
Visible signs of use
Verified parts
Battery for daily use
Example image
Screen
May have micro-scratches
Verified parts

Fair $298.00
Good $334.00
Excellent Sold out
Premium Sold out

Select storage

Select storage

128 GB $298.00

Select the color

Black $298.00

Galaxy S21 Ultra 5G 128GB - Black - Locked AT&T

Galaxy S21 Ultra 5G • Locked AT&T

Fair
128 GB
Black

$298.00

Save $1,202.00

Proudly refurbished by Lastoftheloot

Free delivery by Jun 22 - 23

Express delivery by Jun 17 - 18 from $15.00

Comes with

Compatible charging cable

Often bought together

Galaxy S21 Ultra 5G • Locked AT&T

Black • 128 GB • Physical SIM + eSIM

Refurbished price:$298.00

Versus $1,500.00 new

AirPods Pro 2 (2023)

Refurbished price:$133.00

Total price: $431.00

These items might be sold and shipped by different sellers.

Pairs well with

AirPods Pro 2 (2023)Good
(657)
Refurbished price:$133.00
AirPods 2 (2019)Good
(3,304)
Refurbished price:$85.04
AirPods Pro 2 (2022)Good
(809)
Refurbished price:$135.00
Price drop
AirPods Max (2024)Good
(48)
Refurbished price:$350.00
Save $35.00
Last lowest price : $385.00
The lowest price for this product in this exact configuration on Back Market in the 30 days prior to 6/15/2026. This reference will update on 6/22/2026.
AirPods Pro 3 (2025)Good
(134)
Refurbished price:$185.00
AirPods 3 (2021)Good
(1,497)
Refurbished price:$85.00
AirPods 4 (2024)Good
(144)
Refurbished price:$110.00
AirPods 4 (ANC) (2024)Good
(162)
Refurbished price:$115.00
AirPods Pro 1 (2021)Excellent
(642)
Refurbished price:$109.00
AirPods Pro 1 (2019)Good
(2,933)
Refurbished price:$107.72
AirPods Max (2020)Good
(184)
Refurbished price:$313.00
Galaxy S21 Ultra 5G case - TPU - BlackBrand new
(5)
Refurbished price:$20.99

Customer reviews for Galaxy S21 Ultra 5G • Locked AT&T

Overall rating

38 verified reviews

Rating details

Battery
4.5/5
Shipping
4.5/5
Lens & Camera
4.7/5
Accessories
4.3/5
Packaging
4.5/5
Overall performance
4.1/5
Appearance
4.4/5

Reviews

Paul S.
Verified purchase
Reviewed 11/16/25, United States.
The device arrived in a timely manner in a condition and functionality stated in buy Back Market This is my second order using this site I also purchased an s22 ultra and have been very satisfied with both purchases
Galaxy S21 Ultra 5G 128GB - Black - Locked AT&T
Galaxy S21 Ultra 5G 128GB - Black - Locked AT&T
See item
Condition
Good
Light signs of wear. The body may have light micro-scratches. For items with screens, the screen will have no scratches.
Purchased
11/2/25
Debbie L.
Verified purchase
Reviewed 11/10/24, United States.
Phone is perfect for me! So glad I could buy an ATT refurb, since some features are not available on unlocked devices. Replaced the same phone I had, an unlocked S21 Ultra with a cracked screen which would cost more to fix than this refurb, and since ATT service/reception has been going steadily downhill, really appreciate that I can use WiFi calling now. Yeah, I should switch but no guarantee that service would be any better. Totally happy with this purchase!
Galaxy S21 Ultra 5G 128GB - Black - Locked AT&T
Galaxy S21 Ultra 5G 128GB - Black - Locked AT&T
See item
Condition
Excellent
Almost no signs of wear. The body may have very light micro-scratches. For items with screens, the screen will have no scratches.
Purchased
10/31/24
Renee L.
Verified purchase
Reviewed 8/14/23, United States.
I was honestly worried getting a used phone. But I wasn't paying 1000 for a phone. so I went back and worth for couple weeks and I had message company and asked few questions. They was awesome and answered all my questions. so I ordered the phone I wanted and it was here in 3 days. let me tell you. This phone looks brand new. I have had it for couple days and no problems at all. I absolutely love it. I will be buying more stuff from here.
Galaxy S21 Ultra 5G 256GB - Dark Gray - Locked AT&T
Galaxy S21 Ultra 5G 256GB - Dark Gray - Locked AT&T
See item
Condition
Excellent
Almost no signs of wear. The body may have very light micro-scratches. For items with screens, the screen will have no scratches.
Purchased
8/8/23
Mason H.
Verified purchase
Reviewed 10/17/24, United States.
The condition was near perfect though it had minor screen burn in only noticeable if you really look into it
Galaxy S21 Ultra 5G 128GB - Black - Locked AT&T
Galaxy S21 Ultra 5G 128GB - Black - Locked AT&T
See item
Condition
Fair
Signs of wear. The body may have a few visible scratches and dents. Items with screens may have light scratches.
Purchased
10/15/24
Eric H.
Verified purchase
Reviewed 3/5/24, United States.
This is my 3rd purchase from backmartket and I must say, they have never failed to deliver a quality product to me! This phone is in amazing condition it has 1 tiny little scuff on the screen that was maybe ⅛ of an inch long that was super shallow and completely disappeared when I put a screen protector on it!everything else works perfectly and it is a major improvement from my s10 thank your again backmartket I've recommended you to everyone that's said they needed a new phone and plan on purchasing all my tech from you in the foreseeable future if possible
Galaxy S21 Ultra 5G 128GB - Black - Locked AT&T
Galaxy S21 Ultra 5G 128GB - Black - Locked AT&T
See item
Condition
Excellent
Almost no signs of wear. The body may have very light micro-scratches. For items with screens, the screen will have no scratches.
Purchased
2/18/24
Misty L.
Verified purchase
Reviewed 3/26/25, United States.
I got my device and the touch screen was either unresponsive or intermediate... so I got the label, the box and proofed of purchase... I sent it out 16th and got back to the seller on March 20th. so 2 business days would be the 21st, 24th, 25th, and 26th... with messaging back market waking what's going on the I get message back with that I believe is AI they are looking into it and never given me a direct answer just asking me to be patient... I'm losing wages with this problem as that's my works phone....
Galaxy S21 Ultra 5G 128GB - Black - Locked AT&T
Galaxy S21 Ultra 5G 128GB - Black - Locked AT&T
See item
Condition
Fair
Signs of wear. The body may have a few visible scratches and dents. Items with screens may have light scratches.
Purchased
2/26/25
Jake M.
Verified purchase
Reviewed 10/31/24, United States.
I ordered an "excellent" condition phone for a little extra. The phone i got has scratches and dings on the metal body around the edges. Nothing to impair the use of the device, but one can't help feeling a bit ripped off. When you pay extra for condition, you expect to get what you pay for. Lesson learned on this one...
Galaxy S21 Ultra 5G 128GB - Silver - Locked AT&T
Galaxy S21 Ultra 5G 128GB - Silver - Locked AT&T
See item
Condition
Excellent
Almost no signs of wear. The body may have very light micro-scratches. For items with screens, the screen will have no scratches.
Purchased
10/26/24

Everything you ever wanted to know about the Galaxy S21 Ultra 5G • Locked AT&T

Durability
Overall performance
Camera
Screen quality

Dynamic AMOLED 2XScreen type
8 ozWeight
USB-CConnector
Galaxy S21 Ultra 5GModel
128 GBStorage
SM-G998UManufacturer Ref.
40 megapixelsFront camera
1440 x 3200Resolution
1.02SAR body

The Samsung Galaxy S21 Ultra 5G remains a flagship-level smartphone that was first released in January 2021. Known for its large, vibrant display and versatile camera system, it continues to be a solid option for users who need a high-performance Android device. Although it is a couple of generations old, the Galaxy S21 Ultra 5G still offers strong specifications and features that cater to demanding smartphone users.

Key features:

Release Date: January 2021
Display: 6.8-inch Dynamic AMOLED 2X, QHD+ resolution, 120Hz refresh rate
Processor: Exynos 2100 (Global) or Snapdragon 888 (US)
Camera: Quad rear cameras with 108MP main sensor, 10MP periscope telephoto, 10MP telephoto, and 12MP ultra-wide
Connectivity: 5G compatible for fast network speeds
Operating System: Ships with Android 11, upgradable to later versions

Who is this for?

The Samsung Galaxy S21 Ultra 5G is best suited for professionals, content creators, and tech enthusiasts who need a large, high-resolution display and a versatile camera setup. It appeals to users who prioritize multimedia consumption, mobile photography, and multitasking performance. Compared to newer models like the Galaxy S22 Ultra, the S21 Ultra still offers competitive features but may lack some software refinements and camera improvements found in the latest generation.

Pros & Cons: Pros Cons Large, vibrant 120Hz AMOLED display ideal for media and gaming. Bulky size and weight may not suit users preferring compact phones. Versatile quad-camera system with high-resolution main sensor and telephoto zoom. Locked to AT&T network, limiting carrier flexibility. Strong performance with Snapdragon 888 / Exynos 2100 chipset. No microSD card slot for expandable storage.
Why refurbished?

Choosing a refurbished Samsung Galaxy S21 Ultra 5G is an eco-conscious decision that extends the lifespan of a premium device. Back Market ensures all refurbished phones meet strict quality standards through comprehensive testing and certification. Learn more about our quality standards.

Screen type: Dynamic AMOLED 2X
Weight: 8 oz
Connector: USB-C
Model: Galaxy S21 Ultra 5G
Storage: 128 GB
Manufacturer Ref.: SM-G998U
Front camera: 40 megapixels
Resolution: 1440 x 3200
SAR body: 1.02
Network: 5G
Serie: Samsung Galaxy S
Carrier compatibility: AT&T
Main camera: 108 megapixels
OS: Android
Last OS Compatibility: Yes
SAR head: 0.77
Screen size (inches): 6.8
SIM card: Physical SIM + eSIM
Release Year: 2021
Memory (GB): 12 GB
Memory Card Slot: No
Foldable: No
Brand: Samsung
Color: Black
Color (official name): Phantom Black

Welcome to Back Market

The best prices for high-quality reborn tech by sellers we’ve checked and vetted. We don’t mind if you Google us.

Get to know us

1-year warranty
Free standard shipping
Free 30-day returns
Friendly customer service

Choose location

Suggested searches

Popular searches

Galaxy S21 Ultra 5G • Locked AT&T

Restored professionally

Comes with

Often bought together

You may also like

Pairs well with

Customer reviews for Galaxy S21 Ultra 5G • Locked AT&T

Overall rating

Rating details

Reviews

Reviews

Paul S.

Debbie L.

Renee L.

Mason H.

Eric H.

Misty L.

Jake M.

Popular searches

Everything you ever wanted to know about the Galaxy S21 Ultra 5G • Locked AT&T

Durability

Overall performance

Camera

Screen quality

Related articles

iPhone vs. Android: Which OS is Right for You? | Back Market

Android Phone Activation Guide | eSIM or SIM | Back Market

How to factory reset an Android phone (4 quick scenarios) | Back Market

Can you use a Galaxy watch with an iPhone? | Back Market

Best smartwatch for Android: The only guide you need | Back Market

Buying a Refurbished MacBook | What you need to know | Back Market

Understanding prepaid phones and how they work | Back Market

Welcome to Back Market