Eileen Hope Lewis was born in Rotorua, New Zealand, on 16 October 1884, the daughter of Thomas Hope Lewis, a surgeon, and his wife, Ellen Fenton. Both her parents were enthusiastic golfers and she learnt to play at an early age. By 1887 the family had moved to Auckland where Eileen later joined her mother in becoming a member of the Auckland Ladies' Golf Club. She won the club championship in 1903, 1904, 1905, 1907, 1909 and 1914. She is also thought to have been the first woman to obtain a driver's licence; she was to continue driving until she died. At St Paul's Church, Auckland, on 12 December 1905, aged 21, she married 37-year-old Guy Coldham Williams, a sheepfarmer in Wairarapa. His parents, T. C. Williams and his wife, Annie Beetham, both belonged to prominent landowning families there. The couple were to have four children.
After her marriage, Eileen Williams moved to Te Parae, a large Wairarapa sheep station owned by her husband. For some time she was the only woman there. While their homestead was being built, they lived in one of the workers' cottages; Guy, using a horse-drawn scoop, dug out a lake in front of the new house and Eileen set out the gardens. Horticultural pursuits became very important to her.
Eileen was described as a gentle woman who deferred to her authoritarian husband; it is said that he was respected more than loved. However, she was already a successful golf champion, and was determined to pursue her chosen sport. Domestic staff enabled her to do so. In 1904, aged 19, she had won the New Zealand Amateur Match Championship and she went on to win this women's event five more times between 1907 and 1922. Her success could have been greater but the championship was not held during the war years. When her three daughters were old enough, she often played in foursome competitions with them. Her son started the first golf club at Wanganui Collegiate School when he was a pupil there.
Eileen Williams won several provincial championships and was the inaugural winner of the Mellsop Cup Stroke Championship in 1911. She won this event six more times between 1912 and 1925. In 1930 she won the Championship Foursomes of New Zealand with S. Watson, and in 1933 with Winnie Barns-Graham. She won the Australian Women's Championship in 1920 and reached the semi-finals in championship events in Britain and France. In 1933 she managed the New Zealand team that won the first Tasman Cup match with Australia.
Her position not only as a foremost golf player but also as a member of New Zealand's rural élite made her a natural leader. With other women golfers, Eileen Williams was active in the establishment of the New Zealand Ladies' Golf Union in 1911, and is credited with much of its early development. She held many offices, including those of life vice president and patroness. She was a member of the British Veterans' Golf Club and was prominent in the affairs of the Masterton Golf Club.
Around 1939 Eileen and Guy Williams moved from Te Parae to Heretaunga, before finally settling in Masterton by 1941. Known for her contributions to horticulture in Wairarapa, Eileen held office in the Masterton Beautifying Society and was their 'inspiration over many years'. She was an administrator and a life member of the Masterton Horticultural and Industrial Society, her decorative work featuring in many local horticultural shows, and a member of the Iris Society and the Ranfurly Club.
Eileen Williams died suddenly at her home in Masterton on 13 October 1958, survived by her three daughters and son; her husband had died in 1947. She was one of New Zealand golf's outstanding figures and was at the forefront of women's golf for over 25 years. A capable and energetic administrator and supporter of the many clubs and societies to which she belonged, she was particularly remembered for her warm encouragement of young women golfers.