David Yudelovitch was born in Yassi, Rumania, studied both at the "Heder" and "yeshiva" at the same time, took additional studies in foreign languages and general education with the help of private teachers.
In 1883, at 19, he immigrated to Eretz Israel. In Jerusalem he joined the Russian-origin "Bilu" group who put their efforts and labors into founding the "Shahu"(Association for the Return to Vocational Work). He began working for a German who owned a metal and engraving workshop and even excelled in his work. He lived together with his "Bilu" friends who struggled against their dire poverty and malaria. He befriended Eliezer Ben Yehuda and his wife, Dvora, who greatly helped the group and tried to ease their sufferings.
David Yudelovitch was close to Ben Yehuda and especially to his life's work - to revive the Hebrew language. From then on Yudelovitch, himself, also became devoted to the idea.
When his contract at the workshop ended, he travelled to Paris to specialize in the subject. He took advantage of his time there to attend classes in Jewish Science at the Sorbonne which resulted in awakening the desire to try teaching himself. As well, he contacted the Baron Rothschild and his people who dealt with the matters concerning Eretz Israel.
In 1888, with his return to Eretz Israel from France, he was appointed by the Baron Rothschild to be a teacher at the school which had just then been started by Mordechai Lubman. Here, together with Lubman, he began to enforce the use of Hebrew as the main language in the school and to make it the first Hebrew speaking school in the country. He was the first to teach all general subjects in Hebrew and, together with the teachers, Gur and Zipprin, wrote Hebrew text books. Later, he initiated the founding of the first Hebrew kindergarten aimed at giving the young children a head start and providing them with knowledge of the Hebrew language. For this purpose he translated the Pravel system, used in those days, for the kindergarten teacher, Esther Shapira, chosen to run the kindergarten.
He held this post for fourteen years. During his time, Yehuda Leib Gordon's play "Micha Yosef Levenzon" and Ben-Yehuda's play "The Hashmonaim Vision" were put on at the school. In 1892 he founded (together with Y.Gur-Grazovsky) the "Teachers' Meetings" which met in Rishon Le-Zion and was headed by Mordechai Lubman. Here educational problems were clarified and Yudelovitch served as its permanent secretary. That same year he founded (together with Grazovsky and Ben Yehuda) " A Small World" – the first Hebrew children's newspaper in the world; for many years wrote in Ben Yehuda's newspapers, "Hatzvi", "Ha'or" and "Hashkafa" and other newspapers, and, following Ben Yehuda's trial, became the editor responsible for the newspapers before the Turkish government. At the same time and for several years, he worked as village secretary and book-keeper and was the first who initiated and conducted book-keeping in Hebrew according to modern methods. In 1903 the Rishon Le-Zion and Zichron Yaakov winery management sent him to check out the marketing conditions in Asia and the Far East. Together with his marketing activities abroad, he also brought the news of the revival of Eretz Israel to the Jews living in these distant countries. He later published his impressions from his travels in the "Haskafa" newspaper.
Later, when the management of the wineries moved from the Baron's administration to the authority of the winegrowers themselves, he was elected to serve as member of the first Winery Council of the two wineries.
From 1906-1924 he served as representative of "Carmel Mizrachi" in Alexandria, Egypt and during the entire time there he was not only the company representative but also the representative of the Jewish people in Eretz Israel in all their affairs, as described in the words of Tidhar:"…at every private and public opportunity, in front of Jews and non-Jews, he spoke about the existence and rights of the Jewish nation, instilled in the aristocratic Jews a love for Eretz Israel and support for its revival, organized study groups for Hebrew speakers and through additional studies given by him, Hebrew was introduced at the Alliance schools and the Jewish community and when forced to speak French at the Jewish meeting, he expressed his pity that they did not understand their people's language. His office was open for advice, assistance, instruction and endeavor for every Jew who came from Eretz Israel to arrange affairs in Egypt or who passed through on his way to Eretz Israel and government ministers and representatives of other countries saw his office as the Jewish "consulate" in Alexandria and responded to his requests and recommendations in goodwill, as much as possible". (D. Tidhar, vol. 2, p. 570). As a member of the "Free Masons" already in 1900 in Alexandria, he reopened the office of "Socrates", which was founded 50 years earlier, was voted to serve as its president, participated in the founding of new offices and was active in them. In 1921, as a sign of appreciation for his dedicated activities for the "New Masons", the main office in France appointed him member of the Higher Council in Paris - the highest rank in the "Free Masons".
An important activity took place during WWI when there were more than ten thousand Jewish exiles deported by the Turks from Eretz Israel because of their foreign citizenship. He took advantage of his good relations with high ranking personages in the Egyptian government and foreign representatives to obtain help for the exiled. As a result of his activities, the Egyptian government set up a special department to care for the Jewish exiles, allowed them the use of two large palaces belonging to the governor, Abas Hilmi, and opened schools, hospitals and workshops for them. He also assisted in the founding of the "Mule Drivers' Battalion" and helped the "Bilu" group in their activities in Egypt.
In 1924 David Yudelovitch returned to Rishon Le-Zion where he continued his work at "Carmel Mizrachi" and was a member of the Inspection Committee of the wineries. He continued with this work until his retirement at an old age.
At the same time, he took part in public activities in the village: as a speaker on "affairs of state" of different countries, he participated in the "Reading Evenings" which took place in the village's Community Hall; served as member of School Committee; continued his literary and journalism work which he began already during his early years in Jerusalem and wrote articles in "Haaretz", "Post Today", "Davar" and in newspapers appearing in foreign languages, such as the Polish "Pshishlotz", the Rumanian "Kisaritol" and others. He often signed his articles "Yehuda-Leib-Ish"; translated books from French and German into Hebrew andtogether with the French author, Tibot, wrote "The History of Sara Bernhard"; wrote the first book in Hebrew on the "Free Masons"; edited and published two volumes on "The History of Journalism in Eretz Israel" (1936, 1936); collected material for a large archive about the history and revival of the settlement ("yishuv") including a rich collection about the Baron Rothschild.
In his later years he dedicated himself to investigating and documenting the history of Rishon Le-Zion and was the primary editor of the monumental book, "Rishon Le-Zion, 1882-1941".