Eligibility Criteria  

1. Relationship Requirement: You must be in a genuine and subsisting relationship with a person who is settled in the UK or a British citizen. The relationship must have lasted for at least two years prior to the date of application. Evidence of cohabitation and financial interdependence is required to demonstrate the genuineness of the relationship.  
2. Financial Requirement: Your British or settled partner must meet the minimum income threshold set by the UK government. As of the latest guidelines, the sponsor (partner in the UK) must have a minimum annual income of £18,600. This threshold increases if there are dependent children involved. Additional income sources such as savings, pensions, or non-employment income may also be considered.  
3. Accommodation Requirement: You must have adequate accommodation for you and your dependents without relying on public funds. The accommodation must meet the UK's housing standards and not be overcrowded.  
4. English Language Requirement: You must demonstrate proficiency in the English language by passing an approved English language test at the required level. However, exemptions may apply if you are a national of a majority English-speaking country or have completed a degree taught in English.  
5. Intentions to Live Together: You and your partner must intend to live together as a couple in the UK. You need to provide evidence of your relationship, such as joint financial commitments, correspondence, and photos together.  
6. Immigration History: You must have a clean immigration history, meaning you have not breached any UK immigration laws or been refused entry to the UK.  
7. Health Requirement: You may need to undergo a tuberculosis (TB) test if you are applying from a country where TB is prevalent. You must also disclose any serious health conditions that could require costly medical treatment in the UK.  

Application Process  

1. Prepare Documentation: Gather all necessary documents to support your application, including evidence of your relationship, financial documents, accommodation details, English language test results, and proof of your intentions to live together.  
2. Complete Online Application: Apply online through the UK government's visa application website. Fill out the application form accurately, providing all required information.  
3. Biometric Appointment: Schedule and attend a biometric appointment at a designated visa application centre to have your fingerprints and photograph taken.  
4. Submit Supporting Documents: Upload scanned copies of your supporting documents online or submit them at the visa application centre.  
5. Pay Fees: Pay the visa application fee and the Immigration Health Surcharge (IHS) if applicable.  
6. Attend Interview (if required): In some cases, you may be required to attend an interview as part of the application process.  
7. Wait for Decision: Once you have submitted your application and supporting documents, wait for a decision on your visa application. The processing time can vary depending on your location and individual circumstances.  
8. Receive Decision: You will be notified of the decision on your visa application. If approved, you will receive a visa vignette in your passport, allowing you to travel to the UK.  
9. Enter the UK: Once you have received your visa, you can travel to the UK within the validity period of the visa.  

Conclusion  

Obtaining a UK unmarried partner visa involves meeting various eligibility criteria, providing supporting documentation, and following the application process outlined by the UK government. By understanding and fulfilling the requirements, you can increase your chances of a successful visa application and join your partner in the United Kingdom.