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Top Climate tech companies in London

Companies decarbonising power, transport, agriculture, and industry. Filtered to companies headquartered in London.

Built from a search like: “Top Climate tech companies in London”

Ranked by current headcount across Climate tech companies headquartered in London. Refreshed daily.

  1. 1
    SLR Consulting· London, England, United Kingdom
    • Series C
    • 4.1k employees
    • Founded 1994
  2. 2
    Equans UK & Ireland· London, England, United Kingdom
    • Grant
    • 2.3k employees
  3. 3
    Safetykleen· Brentford, England, United Kingdom
    • 1.4k employees
    • Founded 1973
  4. 4
    CDP· London, England, United Kingdom
    • Grant
    • 1.2k employees
    • Founded 2000
  5. 5
    Anthesis Group· London, England, United Kingdom
    • Private equity
    • 894 employees
    • Founded 2013
  6. 6
    Trojan Technologies· London, Ontario, Canada
    • 780 employees
    • Founded 1947
  7. 7
    Temple· London, England, United Kingdom
    • 503 employees
    • Founded 1997
  8. 8
    Energy Saving Trust· London, England, United Kingdom
    • Seed
    • 470 employees
    • Founded 2024
  9. 9
    The Carbon Trust· London, England, United Kingdom
    • Series unknown
    • 407 employees
    • Founded 2001
  10. 10
    Lynker· Leesburg, Virginia, United States
    • 389 employees
    • Founded 2007
  11. 11
    Janus Global Operations LLC· Lenoir City, Tennessee, United States
    • 376 employees
    • Founded 1987
  12. 12
    Ambipar | Europe· London, England, United Kingdom
    • 347 employees
  13. 13
    Systemiq Ltd.· London, England, United Kingdom
    • Series unknown
    • 333 employees
    • Founded 2016
  14. 14
    Reconomy· London, England, United Kingdom
    • 319 employees
    • Founded 1994
  15. 15
    International Water Association· London, England, United Kingdom
    • 288 employees
    • Founded 1947
  16. 16
    Climate Group· London, England, United Kingdom
    • 279 employees
    • Founded 2004
  17. 17
    Reconomy Connect· London, England, United Kingdom
    • 277 employees
    • Founded 1994
  18. 18
    Etude· London, England, United Kingdom
    • 264 employees
    • Founded 2012
  19. 19
    INTEC Energy Solutions· London, England, United Kingdom
    • 262 employees
  20. 20
    enfinium· London, England, United Kingdom
    • Debt
    • 260 employees
    • Founded 2021
  21. 21
    Tersus (Marlowe Environmental Services)· Rainham, England, United Kingdom
    • 258 employees
    • Founded 1985
  22. 22
    Hydro Cleansing· Croydon, England, United Kingdom
    • 258 employees
    • Founded 2000
  23. 23
    JD Ross Energy· London, England, United Kingdom
    • 222 employees
    • Founded 2015
  24. 24
    Salix· London, England, United Kingdom
    • Grant
    • 220 employees
    • Founded 2004
  25. 25
    Carbon Clean· London, England, United Kingdom
    • Series C
    • 197 employees
    • Founded 2009

Find engineers at Climate tech companies in London

London has long been a hub for Climate tech, and the list above ranks the largest Climate tech companies headquartered there by current headcount, drawn from public LinkedIn and Crunchbase records. With 449 matching companies in our index, this is a good map of where the Climate tech talent in Londonlives — useful whether you’re recruiting, partnering, or sizing a market.

The biggest Climate tech companies in London tend to be the gravitational centres for specialised talent — senior engineers, ML researchers, applied scientists, designers — while the smaller ones compete on speed, equity, and proximity to founders.

Refolk converts this list into a live search. Ask for “Climate tech engineers in Londonhiring senior staff” or “founders of Climate tech companies in Londonwho left in the last 12 months” and Refolk returns a ranked shortlist with the evidence that earned each person a spot.

How this list is built

Refolk pulled Climate tech companies headquartered in London from public LinkedIn and Crunchbase records, ranked them by current employee count, and kept those with at least 10 employees. The list refreshes once a day.

Last refreshed: Thu, 07 May 2026 08:52:24 GMT

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