The only other contender for the mayoral position was former mayor and councillor Clare Le Serve, the sole survivor of the 2012-16 council.
Cr Rothfield, who was elected early this evening, continues a recent tradition of a newbie taking up the top role. Cr Le Serve was elected mayor in the first year of her council term in 2012.
Cr Rothfield first lived on Phillip Island as an infant back in mid 1950s, as her family came from the island, and moved back to Rhyll about 11 years ago.
She is president of the Rotary Club of Phillip Island and San Remo, secretary and treasurer of the Phillip Island Cemetery Trust, accessions office for the Phillip Island and District Historical Society, a committee member of the Phillip island Golf Club and a member of the Rhyll Progress Association and the Phillip Island Progress Association.