Tiwari took away Rs 1 crore prize money, beating likes of WWE star The Great Khali, actors Ashmit Patel and Dolly Bindra at Salman Khan-hosted grand finale in Lonavala.
The Great Khali garnered second highest number of votes, while Ashmit Patel stood third.
After emerging victorious, an overwhelmed and emotional Tiwari said, "I am very happy for winning Bigg Boss.
I never expected that I would win this show."
Earlier three seasons of the show were won by actors Rahul Roy, Ashutosh Kaushik and Vindu Dara Singh, respectively.
On where she would spend the prize money, Tiwari, a single mother, said "I will use this for future of my daughter."
During her stay in the house, Shweta was active in the household chores and her behaviour was cool and composed throughout the show.
Runner-up Khali congratulating Tiwari said, "I am happy for her. She was really nice at the Bigg Boss house."
The three runners-up got a bike each, while actor Sameer Soni received a Chevrolet Cruze as a prize for being the boldest and most stylish participant of this season.
Apart from Salman Khan`s dance on Dabangg number `Peeni hai`, the grand finale also saw performances by former contestants Sara Khan, Veena Malik, Aanchal Kumar and Manoj Tiwari.
`Bigg Boss 4` started with 14 contestants, and had two wild card entries in subsequent weeks, with a three-day guest appearance by Hollywood actress Pamela Anderson.