Karaite Judaism or Karaism is a non-Rabbinical Jewish sect characterized by the recognition of the written Tanakh alone as its supreme authority in halakha (religious law) and theology. Karaites believe that all of the divine commandments which were handed down to Moses by God were recorded in the written Torah without any additional Oral Torah or explanation.

Unlike mainstream Rabbinic Judaism (aka Talmudic Judaism), which regards the Oral Torah, codified in the Talmud and subsequent works, as authoritative interpretations of the Torah, Karaite Jews do not treat the written collections of the oral tradition in the Midrash or the Talmud as binding.

Karaite interpretation of the Torah strives to adhere to the plain or most obvious meaning (peshat) of the text; this is not necessarily the literal meaning of the text—instead, it is the meaning of the text that would have been naturally understood by the ancient Hebrews when the books of the Torah were first written—without the use of the Oral Torah. By contrast, Rabbinic Judaism relies on the legal rulings of the Sanhedrin as they are codified in the Midrash, Talmud, and other sources to indicate the authentic meaning of the Torah. Karaism holds every interpretation of the Torah to the same scrutiny regardless of its source, and teaches that it is the personal responsibility of every individual Jew to study the Torah, and ultimately to decide personally its correct meaning. Karaites may consider arguments made in the Talmud and other works, but without exalting them above other viewpoints.

According to the Karaite Mordecai ben Nissan (born 1650), the ancestors of the Karaites were a group called Sons of Zadok during the Second Temple period. Historians have argued over whether Karaism has a direct connection to the Sadducees dating back to the end of the Second Temple period (70 CE) or whether Karaism represents a novel emergence of similar views. Karaites have always maintained that while there are some similarities to the Sadducees due to the rejection of rabbinical authority and of the Oral Law, there are major differences.

According to Rabbi Abraham ibn Daud, in his Sefer ha-Qabbalah (written c. 1160), the Karaite movement crystallized in Baghdad in the Gaonic period (c. 7th–9th centuries) under the Abbasid Caliphate in present-day Iraq. This is the view universally accepted among Rabbinic Jews. However, some Arab scholars claim that Karaites were already living in Egypt in the first half of the seventh century, based on a legal document that the Karaite community in Egypt had in its possession until the end of the 19th century, in which the first Islamic governor ordered the leaders of the Rabbinite community against interfering with Karaite practices or with the way they celebrate their holidays. It was said to have been stamped by the palm of Amr ibn al-ʿĀṣ as-Sahmī, the first Islamic governor of Egypt (d. 664), and was reportedly dated 20 AH (641 CE).

At one time, Karaites made up about 10 percent of the Jewish population. However as of 2013, an estimated 30,000 to 50,000 Karaites resided in Israel, with smaller communities in Turkey, Europe and the United States. A 2007 report estimated that, of 30,000 worldwide, more than 20,000 descend from those who made aliyah from Egypt and Iraq to Israel. The largest Karaite community today resides in the Israeli city of Ashdod.

Some scholars trace the origin of Karaism to those who rejected the Talmudic tradition as an innovation. Judah Halevi, an 11th-century Jewish philosopher and rabbi, wrote a defense for Rabbinic Judaism entitled Kuzari, placing the origins of Karaism in the first and second centuries BCE, during the reign of Alexander Jannaeus ("King Jannai"), king of Judaea from 103 to 76 BCE:

After him came Judah b. Tabbāi and Simon b. Shētaḥ, with the friends of both. At this period the doctrine of the Karaites arose in consequence of an incident between the Sages and King Jannai who was a priest. His mother was under suspicion of being a 'profane' woman. One of the Sages alluded to this, saying to him: 'Be satisfied, O king Jannai, with the royal crown, but leave the priestly crown to the seed of Aaron.' His friends prejudiced him against the Sages, advising him to browbeat, expel, and scatter or kill them. He replied: 'If I destroy the Sages what will become of our Law?' 'There is the written law,' they replied, whoever wishes to study it may come and do so; take no heed of the oral law.' He followed their advice and expelled the Sages and among them Simon b. Shētaḥ, his son-in-law. Rabbinism was laid low for some time. The other party tried to establish a law built on their own conception, but failed, till Simon b. Shētaḥ returned with his disciples from Alexandria, and restored tradition to its former condition. Karaism had, however, taken root among people who rejected the oral law, and called all kinds of proofs to their aid, as we see to-day. As regards the Sādōcaeans and Boēthosians, they are the sectarians who are anathemised in our prayer.