Is an IGNOU degree valid for UPSC?

You will be qualified. It should be a well-known university. You can check the eligibility criteria listed below:

Academic Qualification for IAS Exams: 

• The candidate must have a degree from one of the Universities established by an Act of the Central or State Legislatures in India, or from another educational institution established by an Act of Parliament or declared to be deemed as a University under Section 3 of the University Grants Commission Act, 1956, or an equivalent qualification.

• Candidates who have taken or plan to take the qualifying exam and are awaiting results are also eligible to take the Preliminary Examination. All such candidates who qualify to take the Civil Services Main Examination must submit proof of passing the said exam with their application for the Main Examination.

• In exceptional cases, the UPSC may treat a candidate who lacks the aforementioned requisite qualification as an eligible candidate if he or she has passed an examination administered by another institution, the standard of which, in the Commission's opinion, justifies his or her admission.

• Candidates with professional and technical qualifications that the government recognizes as equivalent to professional and technical degrees.

• Candidates who have completed the final year of their MBBS or any other Medical Examination but have yet to complete their internship can also sit for the Main Examination. They must, however, submit a certificate from the University / Institution's concerned authority confirming that they passed the final professional medical examination along with their Main Examination application. 

At the interview stage, they must then produce a certificate from a competent authority stating that they have completed all of the requirements for the award of the Medical Degree (including internship).