Alphabetically Union List - L
- L&K Labour Union of Thailand
- LABOUR LAW KEEPER MASSES UNION
- Labour Union of Thai Benkan
- Lady Bird Garment Industry Labour Union
- Laemthong Protein Foods 243 Labour Union
- Lagoona Beach Resort and Hotel Business Phuket Workers Union
- Lagoona Golf Club Workers Union
- Lankrabue Crude Workers Union
- Le Meridien Phuket Workers Union
- Leader of Samsung Labour Union
- Leather Bleash Industry Labour Union of Thaialnd
- Leather Garment Workers Union of Thailand
- Leather Products of Workers Union of Thaialnd
- Lek Phet Labour Union
- Lek Thai Bangpu Labour Union
- Leon Wig Maker Labour Union
- Leshin Industrial Workers Union of Thailand
- Lever Brothers Workers Union
- Liang Hong Workers Union
- Life and Asset Guardian Labour Union
- Light House Workers Union
- Lighting Workers Union
- Lime Acid Industry Labour Union
- Linfox Transport Workers Union
- Linfox Workers Union
- Link Car Line Employees Union
- Linkwolrd Connection Labour Union
- Lion and Affiliates Workers Union of Thailand
- Lion Tris Workers Union of Thailand
- Liquor Distilley Enterprise Workers Union
- Logistic Driver Labour Union
- Logistics Relation Workers Union(LRWU)
- Lois Glue Tape Product Labour Union
- Longyear Industrial Workers Union
- Lucky 3 Textile Labour Union
- Luckytex Labour Union
- Luckytex Thai Factory 2 Workers Union
- Lucut Thailand workers' union
- Lufthansa Airlines Labour Union
- Lupin Labour Union
