Firm Back Support King Mattresses

Firm Back Support King Mattresses can help you narrow your search for a spacious sleep surface with a firmer feel. Explore a range of king-size mattresses at Mattress Firm to find the comfort and support that fit your sleep preferences, bedroom and budget.

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Beautyrest PressureSmart 2.0 Firm 11" Mattress

Starting at

$1099⁹⁹

$2199⁹⁹

$1100 OFF

Firm Comfort, best for

Back, Stomach Sleepers
Temperature
Bed Partner
Pain
Toss and Turn

FREE ADJUSTABLE BASE ³ with code ELEVATE

Sleepy's Basic Memory Foam Firm Mattress

3213

Starting at

$299⁷⁷

$999⁹⁹

$700 OFF

Firm Comfort, best for

Back, Stomach Sleepers
Pain
Bed Partner
Temperature
Toss and Turn
Support

Sleepy's Basic Innerspring Firm Mattress

8676

Starting at

$249⁹⁹

Firm Comfort, best for

Back, Stomach Sleepers
Temperature
Pain
Bed Partner
Allergies
Toss and Turn

Sleepy's Rest Firm 2.0 Innerspring Mattress

7001

Starting at

$449⁹⁹

Firm Comfort, best for

Back, Stomach Sleepers
Pain
Bed Partner
Temperature
Toss and Turn

Sleepy's Basic Foam Mattress

1412

Starting at

$259⁹⁹

$649⁹⁹

$390 OFF

Firm Comfort, best for

Back, Stomach Sleepers
Pain
Temperature
Bed Partner
Toss and Turn

Beautyrest Silver BRS900 11.75" Extra Firm Mattress

3296

Starting at

$709⁹⁹

$1699⁹⁹

$990 OFF

Extra Firm Comfort, best for

Back, Stomach Sleepers
Temperature
Pain
Allergies
Bed Partner
Toss and Turn

FREE ADJUSTABLE BASE ³ with code ELEVATE

Beautyrest BR800 11.25" Firm Mattress

2233

Starting at

$619⁹⁹

$1299⁹⁹

$680 OFF

Firm Comfort, best for

Back, Stomach Sleepers
Toss and Turn
Pain
Bed Partner
Temperature

FREE ADJUSTABLE BASE ³ with code ELEVATE

Stearns & Foster Estate 14.5" Firm Mattress

1809

Starting at

$2799⁰⁰

$3099⁰⁰

$300 OFF

Firm Comfort, best for

Back, Stomach Sleepers
Pain
Bed Partner
Temperature
Allergies
Toss and Turn

Receive $300 Instant Gift⁴ with purchase.

Sealy Essentials Sudley 8.5" Firm Mattress

989

Starting at

$499⁹⁹

$999⁹⁹

$500 OFF

Firm Comfort, best for

Back, Stomach Sleepers
Pain
Temperature
Bed Partner
Toss and Turn

Beautyrest Silver BRS900-C 13.75" Extra Firm Mattress

1810

Starting at

$859⁹⁹

$1999⁹⁹

$1140 OFF

Extra Firm Comfort, best for

Back, Stomach Sleepers
Temperature
Pain
Bed Partner
Toss and Turn

FREE ADJUSTABLE BASE ³ with code ELEVATE

Beautyrest Silver BRS900 11.75" Medium Firm Mattress

1745

Starting at

$809⁹⁹

$1099⁹⁹

$290 OFF

Medium Comfort, best for

Back, Side, Stomach Sleepers
Allergies
Bed Partner
Temperature
Pain
Toss and Turn

FREE ADJUSTABLE BASE ³ with code ELEVATE

Sleepy's By Sealy Slumber Cushion Firm Mattress

301

Starting at

$1999⁹⁹

Medium Comfort, best for

Back, Side, Stomach Sleepers
Bed Partner
Toss and Turn
Pain
Temperature

FREE ADJUSTABLE BASE ³ with code ELEVATE

Serta Perfect Sleeper Nurture Night 12" Firm Mattress

1186

Starting at

$859⁰⁰

$999⁰⁰

$140 OFF

Firm Comfort, best for

Back, Stomach Sleepers
Pain
Bed Partner
Temperature
Toss and Turn

FREE ADJUSTABLE BASE ³ with code ELEVATE

Tulo Bamboo 6" Firm Green Tea Memory Foam Mattress

5558

Starting at

$729⁹⁹

Firm Comfort, best for

Back, Stomach Sleepers
Pain
Bed Partner
Temperature
Toss and Turn

FREE ADJUSTABLE BASE ³ with code ELEVATE

Nectar Classic 12" Firm Memory Foam Mattress

231

Starting at

$899⁰⁰

$1399⁰⁰

$500 OFF

Firm Comfort, best for

Back, Stomach Sleepers
Pain
Bed Partner
Temperature
Toss and Turn

Serta Perfect Sleeper Oasis Sleep 12" Extra Firm Mattress

905

Starting at

$1109⁰⁰

$1399⁰⁰

$290 OFF

Extra Firm Comfort, best for

Back, Stomach Sleepers
Pain
Temperature
Bed Partner
Toss and Turn

FREE ADJUSTABLE BASE ³ with code ELEVATE

Sealy Essentials Spruce 5.5" Firm Mattress

1371

Starting at

$549⁹⁹

$949⁹⁹

$400 OFF

Firm Comfort, best for

Back, Stomach Sleepers
Pain
Temperature
Bed Partner
Toss and Turn

Tempur-Pedic TEMPUR-ProAdapt 2.0 12" Firm Mattress

4992

Starting at

$3799⁰⁰

$4199⁰⁰

$400 OFF

Firm Comfort, best for

Back, Stomach Sleepers
Pain
Allergies
Bed Partner
Toss and Turn
Temperature

Receive $300 Instant Gift⁴ with purchase + Calm app 3-month free trial

Beautyrest Black Series Three 15" Firm Mattress

2224

Starting at

$4199⁰⁰

$4799⁰⁰

$600 OFF

Firm Comfort, best for

Back, Stomach Sleepers
Pain
Bed Partner
Temperature
Toss and Turn

$300 ⁶ adjustable base instant gift with purchase.

Purple RestorePlus 13" Firm Hybrid Mattress

1667

Starting at

$3600⁰⁰

$4399⁰⁰

$799 OFF

Firm Comfort, best for

Back, Stomach Sleepers
Pain
Allergies
Bed Partner
Toss and Turn
Temperature

Tempur-Pedic TEMPUR-LuxeAdapt 2.0 13" Firm Mattress

1449

Starting at

$5099⁰⁰

$5599⁰⁰

$500 OFF

Firm Comfort, best for

Back, Stomach Sleepers
Pain
Temperature
Allergies
Bed Partner
Toss and Turn

Receive $300 Instant Gift⁴ with purchase + Calm app 3-month free trial

Serta Perfect Sleeper Oasis Sleep 14.5" Firm Pillow Top Mattress

1178

Starting at

$1139⁰⁰

$1399⁰⁰

$260 OFF

Firm Comfort, best for

Back, Stomach Sleepers
Pain
Bed Partner
Temperature
Toss and Turn

FREE ADJUSTABLE BASE ³ with code ELEVATE

Serta Perfect Sleeper Sleep Excellence Extra Firm Mattress

955

Starting at

$1449⁹⁹

$1999⁹⁹

$550 OFF

Extra Firm Comfort, best for

Back, Stomach Sleepers
Pain
Toss and Turn
Temperature
Bed Partner

FREE ADJUSTABLE BASE ³ with code ELEVATE

Tempur-Pedic TEMPUR-Adapt 11" Medium Hybrid Previous Generation Mattress

931

Starting at

$2239⁷⁷

$3199⁰⁰

$959 OFF

Medium Comfort, best for

Back, Side, Stomach Sleepers
Temperature
Pain
Bed Partner
Toss and Turn

Sleepy's By Sealy Slumber Firm Mattress

705

Starting at

$419⁹⁹

$1699⁹⁹

$1280 OFF

Firm Comfort, best for

Back, Stomach Sleepers
Bed Partner
Toss and Turn
Pain
Temperature

Serta Perfect Sleeper Pacific Peace 12" Hybrid Firm Mattress

242

Starting at

$1109⁰⁰

$1399⁰⁰

$290 OFF

Firm Comfort, best for

Back, Stomach Sleepers
Pain
Bed Partner
Temperature
Toss and Turn

FREE ADJUSTABLE BASE ³ with code ELEVATE

A firm back support king mattress can provide the stable, supportive feel many sleepers want for a more comfortable night’s rest. Designed with responsive comfort layers and durable support cores, firm king mattresses help create an even sleep surface that keeps your body supported from edge to edge. A well-constructed mattress may also help promote neutral spinal alignment by balancing cushioning with dependable support, especially for back and stomach sleepers who prefer less sink. Look for features such as reinforced edges, individually wrapped coils, zoned support and breathable materials to help reduce motion transfer while maintaining a cool, comfortable sleep environment. Because firmness is a personal preference, the best mattress for back support should feel supportive without creating uncomfortable pressure around the shoulders, hips or lower back Mattress Firm makes it easier to compare king mattresses for firm back support, including innerspring, hybrid, memory foam and adjustable-compatible options. A king mattress provides generous space for couples and solo sleepers, while a supportive foundation or adjustable base can further enhance comfort and make it easier to find a relaxing sleep position. Consider your preferred sleeping position, body type, pressure relief needs and ideal firmness level before choosing a firm king mattress. Sleep Experts® can help you compare materials and support systems so you can find a comfortable mattress that suits your sleep style and helps you get better zzz's night after night. For personalized guidance, visit a Mattress Firm store or explore king mattresses online at mattressfirm.com

What makes a mattress feel firm? + -

A firm mattress typically has a denser comfort layer and a supportive core that creates a more solid sleep surface with less sink.

Which mattress materials are commonly used in firm mattresses? + -

Firm mattresses may feature innersprings, foam, latex or hybrid construction. Each material creates a different feel, from responsive and buoyant to more contouring.

Are firm mattresses available with different comfort feels? + -

Yes. Firm mattresses can include quilted covers, cushioning layers and comfort materials that add surface softness while maintaining a firm overall feel.

How do I choose the right firmness for my sleep position? + -

Consider how you typically sleep and the feel you prefer. Back and stomach sleepers often look for a more solid surface, while side sleepers may prefer added cushioning at the shoulders and hips.

Can I use a firm mattress with an adjustable base? + -

Some firm mattresses are compatible with adjustable bases. Check the mattress specifications to confirm compatibility before pairing it with a base.