The 16-year-old was known for her dance videos and had more than 1.1 million followers on TikTok.
Police were called 9.16pm on Wednesday and Siya was taken to hospital but was declared dead on arrival, the Times of India reports.
Over the weekend, her phone, laptop and other devices will examined and family members interviewed once they were over the initial shock, said police.
The teenager had been receiving “threats” on the internet, but police said they were unable to confirm the motive at this stage of the investigation, the Mail reports.
The news of Siya’s death was confirmed by her manager Arjun Sarin, who managed all her work and endorsements.
He said: “This must be due to something personal… work wise she was doing well.
“I had a word with her last night for a new project and she sounded normal.
“Me and my company Fame Experts manage lots of artists and Siya was a bright talent. I am heading to her home in Preet Vihar.”
Her videos portrayed the image of the girl next door and she also posted snippets of her family life.
On Father’s Day, she posted a video with her father and wrote” “I love you my strength. #Dad.”
Friend and photographer Viral Bhayani said: “Sad news 16-year-old sweet tik-toker @siya_kakkar died by suicide.
“Before publishing this I spoke to her Talent management agency head Arjun Sarin who just spoke to her last night for a song collaboration and he says she was in a good mood and perfectly alright.”
He added: “Even he has no clue what went wrong that she had to go this way.
“You go through her videos and you can see she was so good in her content, it’s really sad that she chose this path.
“If you are feeling depressed please do not do this.”
Kakkar lived in Preet Vihar, New Delhi and was active on all the online platforms such as TikTok, Instagram, Snapchat and YouTube.
As well as being popular on Tik Tok she had 104,000 followers on Instagram.
Her last video in which she danced to a Punjabi song was was posted on Instagram six days ago.