[1] She completed her School Leaving Certificate (SLC) from Birendra Sainik Awasiya Mahavidyalaya, Bhaktapur.

[3][4] She told The Nepali Man that Miss Nepal was "a bit far-fetched for her" and described the experience as "a stepping stone" for her.

[6] In 2015, Khadka debuted as a film actress in Suraj Bhusal's Hostel Returns, where she starred alongside Sushil Shrestha, Najir Hussain, and Sunil Rawal.

[9] Her portrayal of Samriddhi was praised by critics,[11] and The Himalayan Times wrote, "Khadka's act is appealing.

[16] In the film, she plays Akansha, a student who wants to travel to Australia to study but struggles with the International English Language Testing System exam required to enter the country.

[16][17] The Kathmandu Post reported that Chhakka Panja 2 earned around 60 million Nepalese rupees within the first six days of release[18] and went on to become the second highest-grossing Nepali film.

[19] When asked about her experience working with the cast members of Chhakka Panja 2, Khadka said, "Ah, I got to learn a lot!

[22] Her performance was praised by Diwakar Pyakurel of Onlinekhabar, who wrote, "Khadka has acted as stubborn late teen; and she does it quite well.

Prakriti Kandel, writing for Nepali Times, praised her, saying:[26] Swastima Khadka's authentic portrayal of Ranakala is refreshing and captivates.

Her hardships are writ large in her sombre expressions and sharp dialogues which give us a nuanced, all-round portrait of her complex psychology.

But overall Ranakala embodies the female shakti.After Bulbul, Khadka appeared in Hajar Juni Samma, and Ghamad Shere the same year.

[28] Sunny Mahat of The Annapurna Express described the film as "a movie you’d want to watch with your female friends, just to see them cringe at the creepy old man trying to find a match for his son".