Language is a tool that every human being must have to communicate with each other. As part of linguistics, sociolinguistics examines the relationship between language and the social environment, including language style. Language style is a person's distinctive way of expressing something in a particular situation so that the other person can know the speaker's intention clearly and precisely. In addition to everyday life, language styles are also found in literary works, such as speeches. This study aims to analyze the various language style scales that influence King Charles III's use of language style, in his first inaugural speech as a King. The researcher uses the theory of language style by Martin Joos, which classifies language style into five scales: frozen, formal, consultative, casual, and intimate. Furthermore, this research is sociolinguistic research that uses qualitative descriptive methods. In collecting data, the researcher watched King Charles III's speech, checked and matched it with the script. In this speech, 27 data of King Charles III's speech represent Joos' language style. The researcher found that King Charles III only used 3 Joos language styles in his inaugural speech: frozen, formal, and intimate. The dominant language style used by King Charles III was formal style. This is because the speech is an official speech and also the speech is delivered to the British people and the whole world.