Former Prime Minister Manmohan Singh, United Progressive Alliance (UPA) Chairperson Sonia Gandhi and General Secretary Priyanka Gandhi were among those who paid homage to the three-time Chief Minister at the party headquarters in the heart of the city.
Madhya Pradesh Chief Minister Kamal Nath and senior leaders Ahmed Patel and Raj Babbar were among others who joined the emotionally charged crowds.
Dikshit's body was transported in a van with a Congress flag hoisted on top. Her sister Rama sat with the body.
Many other Congress leaders and activities followed the van in cars and two-wheelers.
Congress activists explained why they had gathered at the spot despite the heat.
"For over 15 years, we saw Delhi flourishing every day. The amount of greenary and infrastructure that Delhi has today is because of Dikshitji," said Jagdish Sharma, a party worker.
Added Mubeen Firoz, another Delhiite: "Every day in the morning she used to have a public meeting at her home. I remember her listening to every citizen and working hard to make their lives easy."
Earlier, her mortal remains were brought to the Congress headquarters from her residence at Nizamuddin in south Delhi.
Dikshit was the Congress President in Delhi when she suffered cardiac arrest and died on Saturday.
Her mortal remains were kept at her residence in Nizamuddin in south Delhi from Saturday evening until Sunday afternoon.
On Sunday morning, veteran BJP leaders L.K. Advani and Sushma Swaraj and former Jammu and Kashmir Chief Minister Omar Abdullah visited her residence to pay tributes to Dikshit.
The Delhi government has announced a two-day mourning and a state funeral for Dikshit.
( With inputs from IANS )