Rachael Kirk has spent nine of the past 10 weeks at the Christchurch facility while her son, Declan (23 months), has been in hospital.
Declan was born with serious bowel obstruction and cannot process food normally.
He has had five surgical procedures since April.
Mrs Kirk and husband Hayden have divided their time between Dunedin and Christchurch since Declan's birth.
They also have a 4-year-old daughter, Jasmin.
Mrs Kirk urged Otago residents to support today's national appeal for Ronald McDonald House.
''Before Declan was ill, we had never heard of Ronald McDonald House, but it's certainly on the top of my charity list now.
''We know that so many people need assistance throughout their lifetime and it is crucial to have the house there,'' she said.
Since it opened in 2003, Ronald McDonald House South Island has provided accommodation to 265 Otago families.
Mrs Kirk, in Christchurch with Declan this week, said Ronald McDonald House made all the difference to her time away from home.
''The staff are so supportive and have been very welcoming with the whole family, even extended family who have stayed with us. It provides a comfortable, safe environment close to Declan where we can also have family time.''
Having others nearby who understood what the family was going through also helped, she said.
Mr and Mrs Kirk eventually hope to be able to care for Declan permanently at their Dunedin home.
Today, people will be collecting money for Ronald McDonald House throughout the country as part of the annual appeal.
It was the first time a street collection had been held for the Auckland, Wellington and Christchurch houses.
