First made operational on 31st December, 2005, Blue Line or Line 3/4 is one of the longest and busiest lines of Delhi Metro, and it is also the one with the most number of stations. The main line (Line 3) runs from Dwarka Sector 21 to Noida Electronic City, covering a distance of 56.6 km. Line 4, which is the smaller, branch line, begins at Yamuna Bank and runs for 8.7 km till Vaishali. Line 3 has 50 stations, while Line 4 has eight. Both lines use broad gauge (1676 mm) tracks and 25 kV alternating current supplied via overhead wires. The frequency on the line is generally 4 minutes, but it can vary depending on the time of day, whereas the top speed of the trains remains constant at 80 km/h. The trains on the line comprise either six or eight coaches.
Stations on Blue Line
Blue Line 3
| Station | Interchange/Connections | |
| English | Hindi | |
| Noida Electronic City | नोएडा इलेक्ट्रॉनिक सिटी | |
| Noida Sector 62 | नोएडा सेक्टर 62 | |
| Noida Sector 59 | नोएडा सेक्टर 59 | |
| Noida Sector 61 | नोएडा सेक्टर 61 | |
| Noida Sector 52 | नोएडा सेक्टर 52 | Aqua Line (Noida Metro) |
| Noida Sector 34 | नोएडा सेक्टर 34 | |
| Noida City Centre | नोएडा सिटी सेंटर | |
| Golf Course | गोल्फ कोर्स | |
| Botanical Garden | बोटैनिकल गार्डन | Magenta Line |
| Noida Sector 18 | नोएडा सेक्टर 18 | |
| Noida Sector 16 | नोएडा सेक्टर 16 | |
| Noida Sector 15 | नोएडा सेक्टर 15 | |
| New Ashok Nagar | न्यू अशोक नगर | |
| Mayur Vihar Extension | मयूर विहार एक्सटेंशन | |
| Mayur Vihar – I/td> | मयूर विहार – मैं | Pink Line |
| Akshardham | अक्षरधाम | |
| Yamuna Bank | यमुना बैंक | Blue Line (Line 4) |
| Indraprastha | इंद्रप्रस्थ | |
| Pragati Maidan | प्रगति मैदान | |
| Mandi House | मंडी हाउस | Violet Line |
| Barakhamba Road | बाराखंभा रोड | |
| Rajiv Chowk | राजीव चौक | Yellow Line |
| Ramakrishna Ashram Marg | रामकृष्ण आश्रम मार्ग | |
| Jhandewalan | झंडेवालान | |
| Karol Bagh | करोल बाग | |
| Rajendra Place | राजेंद्र प्लेस | |
| Patel Nagar | पटेल नगर | |
| Shadipur | शादीपुर | |
| Kirti Nagar | कीर्ति नगर | Green Line |
| Moti Nagar | मोती नगर | |
| Ramesh Nagar | रमेश नागर | |
| Rajouri Garden | राजौरी गार्डन | Pink Line |
| Tagore Garden | टैगोर गार्डन | |
| Subhash Nagar | सुभाष नगर | |
| Tilak Nagar | तिलक नगर | |
| Janakpuri East | जनकपुरी पूर्व | |
| Janakpuri West | जनकपुरी पश्चिम | Magenta Line |
| Uttam Nagar East | उत्तम नगर पूर्व | |
| Uttam Nagar West | उत्तम नगर पश्चिम | |
| Nawada | नवादा | |
| Dwarka Mor | द्वारका मोर | |
| Dwarka | द्वारका | Grey Line |
| Dwarka Sector 14 | द्वारका सेक्टर 14 | |
| Dwarka Sector 13 | द्वारका सेक्टर 13 | |
| Dwarka Sector 12 | द्वारका सेक्टर 12 | |
| Dwarka Sector 11 | द्वारका सेक्टर 11 | |
| Dwarka Sector 10 | द्वारका सेक्टर 10 | |
| Dwarka Sector 9 | द्वारका सेक्टर 9 | |
| Dwarka Sector 8 | द्वारका सेक्टर 8 | |
| Dwarka Sector 21 | द्वारका सेक्टर 21 | Orange Line |
Blue Line Route Map
Blue Line 4
| Station | Interchange/Connections |
| Yamuna Bank | Blue Line (Line 3) |
| Laxmi Nagar | |
| Nirman Vihar | |
| Preet Vihar | |
| Karkarduma | Pink Line |
| Anand Vihar | Pink Line; Anand Vihar Terminal; Anand Vihar ISBT |
| Kaushambi | |
| Vaishali |
Further Extension of Blue Line
Both arms of the Blue Line are planned to be further extended into Ghaziabad. The main line (Line 3) is proposed to be extended from Noida Electronic City to connect with the Mohan Nagar station of Red Line via Vasundhara Sector 2. Similarly, the branch line (Line 4) will be extended from Vaishali till Vasundhara Sector 2 via Sahibabad. Thus, the Vasundhara Sector 2 station will become the joining point for both arms of the Blue Line.
Top Attractions Connected by Blue Line
| Top Attraction | Nearest Station | Distance from Nearest Station (Km) |
| Worlds of Wonder | Noida Sector 18 | 1.1 |
| KidZania | Noida Sector 18 | 1.1 |
| Snow World | Noida Sector 18 | 0.9 |
| The Great India Place | Noida Sector 18 | 0.5 |
| Mall of India | Noida Sector 18 | 0.8 |
| Gardens Galleria | Noida Sector 18 | 1.1 |
| Wave Mall | Noida Sector 18 | 0.6 |
| Akshardham Temple | Akashardham | 0 |
| Agrasen Ki Baoli | Barakhamba Road | 0.7 |
| Janpath Market | Rajiv Chowk | 0.4 |
| Connaught Place | Rajiv Chowk | 0 |
| Sacred Heart Cathedral | Rajiv Chowk | 1.4 |
| Jantar Mantar | Rajiv Chowk | 0.6 |
| Gurudwara Bangla Sahib | Rajiv Chowk | 1.4 |
| Karol Bagh Market | Karol Bagh | 0 |
| Jhandewalan Temple | Jhandewalan | 1.2 |
| Birla Mandir | RK Ashram Marg | 1.5 |
| Kali Bari | RK Ashram Marg | 1.8 |
| Rajouri Garden Market | Rajouri Garden | 0.5 |
| Pacific Mall (Tagore Garden) | Subhash Nagar | 0.4 |
| West End Mall | Janakpuri West | 0 |
| Vegas Mall | Dwarka Sector 14 | 0.5 |
| V3S Mall | Nirman Vihar | 0 |
| Pacific Mall (Sahibabad) | Kaushambi | 0.4 |
Other Delhi Metro Lines: Red | Yellow | Green | Violet | Orange | Magenta | Grey | Pink | Rapid Metro
