Is only ielts exam enough to get admission in UK universities for master's?

The basic eligibility requirement to apply for an MS in the UK is a bit more than just an IELTS score. 

IELTS is just a language proficiency test that assesses your ability to read, write and understand English but there are a lot of other things that you need on your application apart from an IELTS score. That being said, here are the few key requirements:
GRE score: GRE is the standard test which analyses your academic fitness for the program that you are applying to. Most colleges consider the GRE as a filtering parameter. Universities receive thousands of applications, and it is difficult to read each one. As a result, they use the GRE to determine whether or not an application is worth reviewing.

Statement of Purpose (SOP): The most essential feature of your application. The statement of purpose is frequently written by students as an extended resume and a glowing story of their accomplishments. The admissions process isn't a contest to see who can boast the most. You must define your long-term objectives and demonstrate how you have progressed toward them. You must also explain how seriously you've considered a master's degree in terms of your profession and objectives. You're on your way to a great admit if you can convey a strong story in a brief and effective document that serves as your SOP. Great SOPs can boost even the most average profiles, while confusing ones can crash even the most powerful.

Letters of Recommendation (LOR): Many Indian applicants ignore this element. Most LORs are little more than a long paragraph of praise. It includes the recommender discussing ten various characteristics of a student and portraying the student as the Lord himself in human form. Such letters will not help you with your application forms. The LORs must work hand in hand with the SOP. There must be two to three qualities of the student that are supported by examples. Technical abilities that are relevant to the student's goals must be backed with examples. Such letters from the appropriate people might possibly get you an easy admission!

Academic Transcripts: You'll have a decent chance at a top university if you have a strong score of 80% or a CGPA of above 3.5. Your transcripts will include information about your grade point average and should be sent to the university.

Resume: Needless to say you need to include your work experience, internships, research papers, projects, extracurricular achievements and basically everything that you can to present your versatile profile. You should although make your, that like your SOP, your resume is not too braggy and keep it crisp.

Like I said, these are the general requirements and there may or may not be any additional requirements for the course or school that you wish to apply to.

So tell me more about the course you wish to pursue and if you have any schools in mind. That way, I’ll be able to check the exact requirements and help you with the information. 

While a strong IELTS score is essential for admission to master's programs in UK universities, it typically isn't the sole requirement. UK universities often have additional criteria for admission, such as academic qualifications, letters of recommendation, statement of purpose, and sometimes standardized test scores like the GRE or GMAT depending on the program. Therefore, while a good IELTS score demonstrates proficiency in English, universities also assess applicants holistically to ensure they meet all requirements for academic success. It's crucial to thoroughly research the admission requirements of your desired universities and programs to ensure you meet all criteria and to prepare a competitive application package. Additionally, some universities may offer English language proficiency waivers for applicants who have completed their previous education in English or who meet certain criteria. It's advisable to reach out to the admissions office of your chosen universities for clarification on their admission requirements and any waivers available. By carefully preparing your application and addressing all admission criteria, you can increase your chances of successfully securing admission to a master's program in the UK.