The name Jennifer, a variation of the Cornish form of Guinevere, emerged in English-speaking countries in the 18th century. Initially more common in Cornwall and Devon, its usage spread, notably among Cornish immigrants in the United States. The name's popularity saw a significant surge in the 20th century, influenced by its use in literature, such as George Bernard Shaw's "The Doctor's Dilemma," and by prominent actresses like Jennifer Jones. A number of popular songs and film productions in the mid-to-late 20th century further contributed to its widespread adoption. The spelling "Jennifer" became the most common form during this period.

Jennifer reached peak popularity in many English-speaking nations during the latter half of the 20th century. It was the number one most popular name for girls in the United States for fifteen consecutive years, from 1970 to 1984. Similar trends were observed in the United Kingdom, Australia, Canada, and several European countries, where it consistently ranked among the top names for decades before gradually declining in usage towards the end of the century and into the early 2000s. The name's origin is linked to the Proto-Celtic "Windo-" meaning "fair one," with cognates in Welsh and Old Irish.

The name Jennifer originates from the Cornish form of Guinevere, with its etymology potentially stemming from Proto-Celtic "Windo-*sēbro," meaning "the fair one." It shares linguistic connections with Welsh Gwenhwyfar and Old Irish Findabair. While early English spellings like "jenefer" existed, they are thought to be derived from the juniper plant. The name began to see use in English-speaking regions from the 18th century, particularly gaining traction in Cornwall. The common nickname "Jenny" likely aided its adoption. In the early 19th century, it was primarily used in Cornwall and Devon, often spelled as Jenifer. Its presence extended to the United States, where it was notably adopted by Cornish immigrants in Wisconsin and also used for males, possibly influenced by Maryland politician Daniel of St. Thomas Jenifer.

Jennifer's widespread recognition significantly increased after 1906, partly due to its use by George Bernard Shaw in "The Doctor's Dilemma." The 1883 novel "Jennifer" by Annie Hall Cudlip also contributed to its literary presence. The 20th century saw "Jennifer" become the dominant spelling. Cultural touchstones such as the films "I Married a Witch" (1942), "Portrait of Jennie" (1948), and "Valley of the Dolls" (1967), along with the acting fame of Jennifer Jones in the 1940s, further boosted the name's profile. Musical influences, including the song "Jenny Rebecca" (recorded by Barbra Streisand in 1965) and popular hits like "Jennifer Eccles" by The Hollies (1968) and "Jennifer Juniper" by Donovan (1968), also played a role. The name's similarity to established popular names like Jane and Jean may have also facilitated its rise.

The name Jennifer experienced remarkable popularity across the globe throughout the latter half of the 20th century. In the United States, it first appeared in Social Security data in 1916 and entered the top 1,000 names in 1938. Its ascent accelerated significantly in the 1940s, reaching the top 100 by 1956. From 1970 to 1984, Jennifer was the most popular name for newborn girls in the U.S. Similar patterns emerged in the United Kingdom, Australia, and Canada, where it was a top 10 name for extended periods. European countries like France, Germany, Sweden, and Italy also saw Jennifer rank highly within their populations during the late 20th and early 21st centuries. While its usage has declined from its peak, it has generally remained within the top 1,000 names in many regions.