Kirkland Signature™ is Costco’s exclusive private-label brand, known for bringing high value across a wide range of products since 1995.
In the supplements category, Costco highlights that Kirkland Signature vitamins are made under rigorous quality controls, and many products carry the USP Verified mark (third-party verification for quality/purity/potency).

Why People Choose Kirkland Signature

• Costco-exclusive value: Kirkland Signature is positioned as a “name-brand quality” alternative at a better value, exclusive to Costco channels.

• Quality controls: Costco states its Kirkland Signature vitamins and supplements are manufactured under rigorous quality controls.

• USP Verified on many items: Costco notes you’ll find USP Verified on many Kirkland Signature supplements—helpful if you care about independent testing standards.

Popular Kirkland Supplement Types (what shoppers usually look for)

Vitamin C

A very common pick is Kirkland Signature Vitamin C 1000 mg (including timed-release options), often labeled USP Verified and typically “free from” certain additives depending on the exact SKU/market.

Calcium + Vitamin D3

Kirkland has well-known calcium products, including:

• Calcium 600 mg + Vitamin D3 (some versions show USP Verified on Costco listing pages).

• Calcium Plus with Vitamin D3 & Minerals 600 mg / 800 IU (Canada listing highlights bones/teeth support + “no GMOs” and several “free-from” claims).

Daily Multivitamins

Kirkland Signature Daily Multi is another “classic” value bottle and appears on Costco with USP Verified noted.

How to Pick the Right Kirkland Supplement

• If you want simple daily immune/antioxidant support → consider Vitamin C (choose dose + tablet type you prefer).

• If you want bone support → look at Calcium + D3 (and minerals if you prefer an “all-in-one” style).

• If you want general coverage → a daily multivitamin is the easiest “one bottle” option.

(Always follow the label directions—especially if you take other medications.)

FAQ

Is Kirkland Signature a Costco brand?
Yes. Kirkland Signature is Costco’s private-label brand and has been a core Costco-exclusive line since 1995.

Are Kirkland vitamins third-party tested?
Costco states that many Kirkland Signature supplements carry the USP Verified mark, which is a recognized third-party verification program.

Do all Kirkland supplements have USP Verified?
No—Costco says “many,” not all. Always check the product label/page for the USP mark.

What are the most popular Kirkland supplements?
Vitamin C, Calcium + Vitamin D3, and daily multivitamins are consistently prominent in Costco’s listings and guides.