Brown Line may refer to:
- Brown line, a process defined as siderotype, a monochrome printing process
- Brown Line (CTA), Chicago
- Brown Line (Delhi Metro), Delhi, India
- Brown Line (Mexico City Metro), Mexico
- Brown Line (Pittsburgh), Pittsburgh, Pennsylvania
- Bakerloo line, London, United Kingdom
- BMT Nassau Street Line, a rapid transit line in New York City
- J/Z (New York City Subway service)
- Tangerang Line of KRL Commuterline, Jakarta, Indonesia
- Paris Metro Line 11, Paris, France
- Thomson–East Coast Line, Singapore
- Ma On Shan line, Hong Kong, China
- Tuen Ma line, Hong Kong, China
- U5 (Berlin U-Bahn), Berlin, Germany
- Wenhu line, Taipei, Taiwan
- Copper Line (San Diego Trolley), San Diego, California
- Metro Bronze Line (Minnesota), Minneapolis–Saint Paul, Minnesota