Dayaratne was born on 29 October 1940 as the youngest child to a family of six in Nawala, Nugegoda. His father Charles Peter Ranatunga was a school principal and his mother Dona Maslin Kolombage was a housewife. He completed education from Ananda Sastralaya, Kotte. After SSC exam, he attended to Zahira College, Colombo and studied in the Maths stream. During school times, he excelled Volleyball and Wrestling.

 

Dayarathna's elder sister, Somalatha Ranatunga is also a singer. Dayarathna's maternal uncle D. M. Kolambage was the first Sinhala announcer at the Radio Ceylon.

 

He was married to Prof. Amara Ranatunga (born as Dona Amara Kasthuriarachchi) where they got registered on 8 August 1963 and celebrated wedding on 30 January 1964. Amara was born on 22 August 1939 at Hanwella as the fifth child of the family with eleven siblings. Her father, Don Wiyolis Kasthuriarachchi was the Head Master of the Hanwella Primary School. Her mother, Dona Alpinona Meegahapola was a housewife. She completed education at Hanwella Central College. In 1961, Amara entered Bhatkhande University in India where she later became the first Sri Lankan Professor in Hindustani classical music in the University of Visual and performing arts.

 

On October 16, 2018, Amara died at the age of 79 while receiving treatment at a private hospital for a heart attack. Her remains were brought to the University of the Visual & Performing Arts at 1.00 pm and later the final rites were held at the Borella General Cemetery on 18 October 2018.

 

The couple has two sons: Nanditha Sarada, Pulasthi Indika and a daughter, Kumudumathie Rupashika. Their son, Pulasthi sang the song Senpathiyan Gena Nawpathiyan Gena with mother Amara at the age of eight.[10] Nanditha is married to Sadhana Abeysekara, who is the granddaughter of late songstress Wasantha Sandanayake. Sadhana's sister, Supriya is also a popular singer in Sri Lanka.