Blue Line or Blueline may refer to:
Transportation
Africa
Blue Line (Lagos Transit), Lagos, Nigeria
Blue Line, part of the Abuja Light Rail Network in Abuja Nigeria
Asia
China
Line 2 (Beijing Subway), Beijing
Island line (MTR), Hong Kong
India
Blue Line (Namma Metro), Bengaluru
Blue Line (Chennai Metro), Chennai
Blue Line (Delhi Metro), Delhi
Blue Line (Hyderabad Metro), Hyderabad
Blue Line (Kolkata Metro), Kolkata
Blue Line (Lucknow Metro), Lucknow
Blue Line (Mumbai Metro), Mumbai
South Korea
Busan Metro Line 4, Busan
Seoul Subway Line 1, Dark Blue Line, Seoul
Seoul Subway Line 4, Light Blue Line, Seoul
Taiwan
Blue line (Taichung MRT), Taichung
Bannan line, Taipei
Others
Blue Line (Bangkok), Bangkok, Thailand
Blue Line (Dubai Metro), Dubai
Cibubur Line of Jabodebek LRT, Jakarta, Indonesia
Manila Light Rail Transit System Line 2, Manila, Philippines
Line 1 (Riyadh Metro), Blue Line, Riyadh, Saudi Arabia
Downtown Line, Singapore
Blue Line (Yokohama), also called Lines 1 & 3, Yokohama, Japan
Blue Line (Jerusalem Light Rail)
Europe
Blue Line (airline), based in France
Blue Line (Lisbon Metro), Portugal
Blue line (Stockholm Metro), Sweden
Blue Line International, a former ferry service in the Adriatic Sea
Barcelona Metro line 5, often called "Línia Blava" (Blue Line), Barcelona, Spain
Barcelona Metro line 6, Barcelona, Spain
Paris Metro Line 2, Paris, France
Piccadilly line, London, England
Sheffield Supertram Blue Line, United Kingdom
Tyne and Wear Metro of Newcastle upon Tyne, UK (Former line)
Victoria line, London, England
North America
Canada
Blue Line (Calgary), Calgary, Alberta
Blue Line (Montreal Metro), Montreal, Quebec
Line 4 (O-Train), the Airport Link of Ottawa's O-Train (Line 4)
Line 3 Scarborough, Toronto, Ontario
Viva Blue, York Region, Ontario
Mexico
Blue Line (Mexico City Metro)
Blue Line (Mexico City Metrobús)
United States
California
A Line (Los Angeles Metro), Los Angeles County
Blue Line (SacRT), Sacramento
Blue Line (San Diego Trolley), San Diego