The singer and musician of 71 years said on News quote his remarks
This is not the first time that the singer takes sides for LGBT rights. She has supported the egalitarian marriage of the United States since 2009. She also pleaded against the bill prohibiting access to bathrooms for trans people in North Carolina.
Already more than 10 million Australians took part in the plebiscite on the issue of marriage equality.
The government will announce the results in November.
Dolly Parton's support for marriage equality is one more support sent to LGBT Australians in the hope that their battle for equality ends with a victory.