He lost his father at an early age, where he was a courageous child who struggled to win the battle of life with his mother in the midst of many hardships during his school days.

[15] Milton's younger son Tharaka is also a singer who sang the songs: Satuṭin Samugena, Virasaka Sitaṭa Lanvelā and A Dine Patan.

As an early singer in the music industry, he became more involved in Hindi singing and also excelled as a guitarist, dholak drummer and tabla player.

Mallawarachchi's vocals on the latter group's Daha Duke Vidyahala and Mal Ravamal led to his discovery by producer Patrick Corea.

These songs were released on the Exvee label as a double set of 78 rpm records in 1969 and gave Mallawarachchi his first popular hit with Oruwaka Pawena.

[2] Mallawarachchi sang songs by Karunaratne Abeysekera, K. D. K. Dharmawardena, Premakirthi de Alwis, Clarence Wijewardena, Upali Danawalawithana, Dharmasiri Gamage, Upali Kannangara, Ajantha Ranasinghe, Shelton Weeraratne, Kularatne Ariyawansa, Ananda Padmasiri, Vernon Perera, Chitrananda Abeysekera, Bandara K. Wijethunga and Vijaya Ramanayake.

In 1974, musician Clarence Wijewardena composed the songs Gana Andure, Eda Rae, Mata Men Ohutada and Maga Thotadhii for an EP release on Gemstone.

[22] Until 1975, he recorded several radio songs composed by Victor Rathnayake such as Seethala Lana Pini, Paa Sinaha Ae, Obe Neth Epa and Sukha Wedana.

It was released on the Silverline label as an EP along with Ran Mudu and two songs - Andanne Epa and Ma Samanalayak - by Shiromie Fernando.

He also sang Sinhala songs for many Pakistani, Nepalese and Bangladeshi films such as Sadākal Rændēvā, Sinha Pæṭaw, Doankāraya, Ayya Nagō, Mis Lankā, Vana Ræjina, Sebaḷiyō, Sāgara Peraḷiya and Oṭṭuyi Bæruvaṭa.

Some of them include: Andurin Piri, Hitavatānangē, Tæluvē Num̆baṭayi, Veedi Konē, Pæṇi Kurullanē, Sændævē Ranvalā, Palathuru Vikuṇana Malanuvanē, Yālē Ayālē Giyā and Punchi Sinā Kohēdo.

[2] Mallawarachchi was a popular live attraction; at a time when there was no TV in Sri Lanka, his appearances at variety shows sponsored by the Ceylon Tobacco Company drew huge crowds.