She was in the intensive care unit (ICU) of Hiranandani Hospital in Mumbai during the time of her death. The cause of her death is not known yet.
Kumar took to Twitter to share the news and also paid tribute to her.
"She was my core. And today I feel an unbearable pain at the very core of my existence. My maa Smt Aruna Bhatia peacefully left this world today morning and got reunited with my dad in the other world," he tweeted.
"I respect your prayers as I and my family go through this period. Om Shanti," he added.
Last evening, Kumar took to the microblogging site to thank well wishers for praying for his mother"s good health.
Kumar flew back to the country on Monday after his mother got admitted to the hospital. He was shooting for his upcoming movie "Cindrella" in the UK.