Patients have a legal right to receive treatment within a maximum 12 weeks of diagnosis after new laws came into force.
The guarantee is one of the rights in the Charter of Patient Rights and Responsibilities, which ministers are required to publish under the Patient Rights (Scotland) Act 2011.
It means patients who need planned inpatient or day case treatment will be covered by a treatment time guarantee, and will have a legal right to receive it within a maximum of 12 weeks from when they are diagnosed and agree to the treatment.
An independent advice service has also been set up to offer advice and support to NHS patients across Scotland.
Health Secretary Alex Neil said: "Patients in Scotland are being treated quicker than ever - and this fast treatment will now be protected by a legal guarantee.
"We are continuing to meet our full 18 weeks from GP referral to treatment target, and now, as part of this journey, once patients are diagnosed and agree to the treatment it will start within 12 weeks.
"In 2007 over 29,000 people were stuck on 'hidden waiting lists' not getting the treatment they needed. I am proud that Scottish patients are reaping the benefits of what the NHS can achieve by protecting the founding principles of the National Health Service.
"The Charter marks an important step forward in giving people more say in their health service. Our health service is remaining in public hands so we want patients to be as involved as possible.
"We know that while our health service does a fantastic job, it is not perfect and that is why we need everyone to give us their feedback so that health boards can continually improve the care they provide.
"We put patients before profits, our NHS belongs to everyone - and everyone can help us to deliver the very best care."