Mandhana dropped anchor to make 60 from 47 balls (10 fours) as she led a resolute fight for India.
India had raced to 44 for no loss at the end of powerplay but Sri Lanka bowlers, led by Kavisha Dilhari (2/36), put up a strong fight.
Towards the end, Ghosh’s vital 30 off 14 balls with four fours and a six took India past the 150-run mark.
Earlier, India skipper Harmanpreet Kaur won the toss and opted to bat.
India did not make any changes to the playing eleven from their semifinal against Bangladesh.
Sri Lanka made one change, bringing in Sachini Nisansala for Achini Kulasuriya.
Teams:
India: Shafali Verma, Smriti Mandhana, Uma Chetry, Harmanpreet Kaur (c), Jemimah Rodrigues, Richa Ghosh (wk), Deepti Sharma, Pooja Vastrakar, Radha Yadav, Tanuja Kanwar, Renuka Singh.
Sri Lanka: Vishmi Gunaratne, Chamari Athapaththu (c), Harshitha Samarawickrama, Hasini Perera, Anushka Sanjeewani (wk), Kavisha Dilhari, Nilakshika Silva, Inoshi Priyadharshani, Udeshika Prabodhani, Sugandika Kumari, Sachini Nisansala.