Macmillan Cancer Support said the city was chosen for its nurse-run call centre because it is a "centre of nursing excellence" in caring for the disease.
The helpline has already dealt with more than 132,000 calls from people across the country – more than it dealt with in all of 2011.
The charity said the increase was partly due to the move to bigger city centre offices in April, which allowed it to recruit three new nurses to answer calls.
A total of 19 nurses are on hand to talk to anyone worried about the disease.
The new centre, in West Nile Street, was officially opened by Deputy First Minister Nicola Sturgeon.
Dorothy Duffy, head of the service, said: "Glasgow is a centre of cancer nursing excellence so there is a huge wealth of experience to draw on here, which makes it the ideal place to site the Macmillan Cancer Support Line.
"Together, our nurses have more than 700 years of cancer nursing experience, which means anyone who calls us for help, whether it is someone with cancer or a family member, can access considerable expertise."
Ms Sturgeon said: "Macmillan Cancer Support offers an invaluable, nationwide service for patients and carers."
The new office also houses its financial guidance team, set up to help those who need advice on dealing with issues such as claiming on health insurance policies or dealing with mortgage issues.
The Support Line is open 8am-8pm, Monday-Friday on 0808 8080000 or see: www.macmillan.org.uk