Short answer — both major international retailers that operate in Malaysia and a growing set of local brands/shops sell sustainable or “eco” collections. Key examples:

1. Big high‑street / global brands (have named sustainable lines available in Malaysia)

• H&M — "Conscious" / Conscious Exclusive sustainable collections. (malaymail.com)
• Zara — "Join Life" / recycled‑material initiatives (Zara/Inditex sustainability programs). (voguebusiness.com)
• Uniqlo (Malaysia) — LifeWear + RE.UNIQLO clothing‑takeback / reuse initiatives. (marketing-interactive.com)
• Nike (Malaysia) — Move to Zero / products made from lower‑impact materials (local site documents their sustainability program). (nike.com)
• adidas (Malaysia) — Primeblue / Primegreen products (recycled ocean plastics / recycled polyester). (adidas.com.my)
• Puma (Malaysia) — "Forever Better" / products made with recycled or more sustainable materials on the Malaysian site. (my.puma.com)
• Levi’s — sustainable denim programmes (Water<Less, repair/recycle messaging available on Levi’s Malaysia resources). (levi.com.my)

2. E‑commerce / multi‑brand platforms with curated sustainable collections

• ZALORA (Malaysia) — sustainability pillar and curated Earth / “sustainable” edits, pre‑loved/upcycling initiatives on the Malaysian site. (zalora.com.my)

3. Malaysian / regionally based sustainable labels and social‑enterprise shops (local, small‑batch, upcycled or fair‑trade)

• Biji Biji (social enterprise: upcycled materials / ethical production; has retail presence in KL and stockists). (bijibiji.co)
• Terrae (Malaysian activewear using Econyl / recycled materials). (thesmartlocal.my)
• Munimalism (botanical/natural dyes; artisanal small‑batch clothing). (tatlerasia.com)
• Earth Heir (social‑impact marketplace selling artisan / refugee‑made apparel & accessories). (earthheir.com)
• Kanoe (modern batik clothing; slow‑fashion, locally made). (kanoewear.com)
• Kayu (handwoven, natural‑material accessories; Malaysian connections / ethical supply chain). (goodfind.io)

Notes and practical tips

• “Sustainable” covers many things (organic/ recycled fibres, lower‑water processes, take‑back/recycling, fair‑trade or artisan/social impact). Check each brand’s product descriptions or sustainability pages for specifics. (adidas.com.my)
• Some large retailers sell limited "sustainable capsules" while most of their business remains conventional fast fashion; critics warn these capsule collections can be small in scope (look for material breakdowns, certifications, or corporate impact reports). (voguebusiness.com)

If you want, I can list specific Malaysian store locations or online stockists for any of the names above (or filter by city, price range, or type such as activewear vs. artisanal).