From Aishwarya Rai-Bachchan to Alia Bhatt, and from Shahid and Mira Kapoor to Anushka Sharma, Kiara Advani, Ananya Panday and Arjun Kapoor, several celebrities from B-Town were present at the welcome party.
Karan's close friends Kajol and Gauri Khan were also present at the bash, which was held late on Thursday night and went on to the wee hours of Friday.
Most of guests dressed up in stylish western outfits, raising the glamour quotient.
After meeting the "Firework" hitmaker, many took to social media to express their fan moments.
Aishwarya posted a picture with Katy, wishing her "more power".
Katy wore a purple shimmery dress, while Aishwarya donned a black dress and accompanied it with a indo western jacket.
Actress Kiara Advani posted a picture on Instagram Story in which she can be seen pouting with her.
"Katy Pout," Kiara captioned the image.
Ananya Panday too uploaded a picture with Katy in which they can be seen sharing smiles with each other.
"Hot and hot," she wrote along with the image.
Several videos are also doing the rounds on the internet in which celebs can be seen having a chit-chat with Katy.
Katy arrived in India on November 12. She even took to her Instagram to share the news of her arrival.
"They say every single cell of your body rejuvenates itself about every 7 years and it's been 7 years since I've been to India so let's just say a brand new me is ready to par-tay..."
Katy is set to perform at One Plus Music Festival.
( With inputs from IANS )