A. R. Rahman, noting her versatility as a singer and her extraordinary voice, employed Swarnalatha for many of his songs. She was one of the most versatile singers of her times, as she was able to sing melodies like "Maalayil Yaaro Manathodu Pesa" from "Sathriyan" or "Porale Ponnuthayi" from "Karuthamma" as well as Rahman's experimental songs like "Mukkabla" from "Kadhalan" or "Mottu Vittadha" from "Pavithra". Swarnalatha was the first female playback singer to fetch the National Award under A. R. Rahman's music direction. She received the award for the song "Porale Ponnuthayi". Once in an interview, she said that she was moved to tears when she finished the recording of this song and received praise from A. R. Rahman. She recorded many songs with music directors Deva, Vidyasagar, Harris Jayaraj, Anu Malik, Shankar-Ehsaan-Loy, Raj-Koti, Yuvan Shankar Raja, Mani Sharma, Hamsalekha and many others. She recorded all the songs originally rendered by Lata Mangeshkar and Shamshad Begum for the Tamil movie "Anarkali" (the dubbed version of the Hindi movie "Mughal-e-Azam") and was praised by the Bollywood music director Naushad Ali. Once during an interview, the interviewer Setu asked her what the best moment of her life had been, expecting her to talk about receiving the National Award. But nobody had expected her to say that the best moment of her life had been when she received the kudos from the legendary Hindi film music director Naushad Ali for her rendition of the songs in Anarkali. Being a non-native Hindi speaker, her pronunciation in Hindi songs was noted as exceptional unlike other prominent singers from South India who had recorded songs in the language.