'twerp' originates from American English slang, first recorded in the early 20th century (c. 1920s). Its exact origin is uncertain; it may be an expressive alteration or variant of dialectal forms such as 'twirp' and may have been influenced by older words like 'twit' (meaning a fool).

'twerp' appeared in U.S. slang publications in the 1920s and circulated as a mild insulting term. It likely developed from earlier colloquial or dialectal forms (for example 'twirp') and stabilized in modern English usage as 'twerp'.

Initially used as a slang insult for a small or contemptible person, the basic sense of 'an insignificant/annoying person' has largely remained; over time its force has often been mild or playful rather than deeply offensive.