Sunny adopted Nisha last year from an orphanage.
In a tweet posted on Saturday, Sunny addressed a note to Nisha saying: "I promise with every ounce of my heart, soul and body to protect you from everything and everyone who is evil in this world. Even if that means giving my life for your safety."
"Children should feel safe against evil hurtful people. Let's hold our children a little closer to us! Protect at all costs," she added.
Sunny and her husband Daniel Weber are also parents to twins Asher and Noah, who were born via surrogacy this year.
Sunny's tweet arrives in the wake of the nationwide outrage over the rape and murder of an eight-year-old child in Kathua.
In strongly worded tweets, celebrities like Sonam Kapoor, Karan Johar, Akshay Kumar, Kalki Koechlin, Farhan Akhtar, Richa Chadha and many others also condemned the heinous crime on social media and asked for justice.
B-town ‘appalled’ by Kathua rape case
The minor girl from the Bakerwal community was kidnapped on January 10; taken to a temple in Rasana village in Kathua.
Her attackers, which included temple official and policemen, drugged and gang raped her over days before finally killing her and dumping her body in forest nearby seven days later.
The girl was attacked to scare away the nomadic Muslim community out of the village.