Englishisation refers to the introduction of English-language influences into other languages. English, as a world language, has had a very significant impact on other languages, with many languages borrowing words or grammar from English or forming calques based on English words. Englishisation is often paired with the introduction of Western culture into other cultures, and has resulted in a significant degree of code-mixing of English with other languages as well as the appearance of new varieties of English. Other languages have also synthesised new literary genres through their contact with English, and various forms of "language play" have emerged through this interaction. Englishisation has also occurred in subtle ways because of the massive amount of English content that is translated into other languages.

Englishisation first happened on a worldwide scale because of the spread of the British Empire and American cultural influence, as the English language historically played a major role in the administration of Britain's colonies and is highly relevant in the modern wave of globalisation. One of the reasons for Englishisation is because other languages sometimes lacked vocabulary to talk about certain things, such as modern technologies or scientific concepts. Another reason is that English is often considered a prestige language which symbolises or improves the educatedness or status of a speaker.

In some cases, Englishisation clashes with linguistic purism or the influence of other prestige languages, as is the case with the contested Hindustani language, which in its Englishised form becomes Hinglish, but which some seek to instead Sanskritise or Persianise in part as a reaction to the colonial associations of the English language within South Asia.

Pidgin English are common throughout Africa, such as West African Pidgin English.

Swahili, which is common in the former British colonies of East Africa, has been intentionally Englishised in order to allow for more conversation around modern technologies and concepts.

The Spanish language, which is widespread in the Americas, typically received loanwards from British English (often through French) until the 1950s, when American English's influence became more prominent.

Spanish as spoken in the United States has significant amounts of English influence, dating back to the early 19th century and America's southwestern territorial expansion into Mexico.

English influences are common in Puerto Rican Spanish, due to the Americanisation of the island since the turn of the 20th century.