Ober-Olm (German pronunciation: [ˈoːbɐ ʔɔlm], lit. 'Upper Olm', in contrast to "Lower Olm") is an Ortsgemeinde – a municipality belonging to a Verbandsgemeinde, a kind of collective municipality – in the Mainz-Bingen district in Rhineland-Palatinate, Germany.

Ober-Olm's neighbours are Mainz-Layenhof, Mainz-Finthen, Mainz-Drais, Mainz-Lerchenberg, Mainz-Bretzenheim, Mainz-Marienborn, Klein-Winternheim, Mainz-Ebersheim, Nieder-Olm, and Essenheim.

Finds in the municipal area have yielded the first clues to settlers here in the 4th century BC. In AD 97, the former consul Vejento had a temple built for the forest goddess Nemetona near his Klein-Winternheim landholding, a richly furnished Roman settlement in the Ober-Olm cadastral area of Villenkeller. Ober-Olm itself arose in the 6th century as a Frankish establishment and had its first documentary mention in 994. The name “Ulmena Superior” from 1190 was formerly associated with elm trees, Ulme being the Modern High German word for this tree; however, this word was not borrowed into German from Latin (ulmus) until the 12th century. The formation of the placename Ulm and an ending —ena is typical for a brook's name, and these were often also used as placenames. It can be assumed that Ulmena was the name that the Germanic settlers between Ober-Olm and Nieder-Olm gave the Selz. The few Roman people left still used the name Salusia for the brook, which was the name that eventually stuck to it. Ulmena, however, remained as well, and clove to both the centres now bearing Olm as part of their names.

In 1582, 1603 and 1857, Ober-Olm was destroyed by devastating fires.

German antisemitism under the Nazis became increasingly difficult in the years prior to World War II. Jews had lived in Ober-olm and surrounding small towns for hundreds of years, from at least the time of the Middle Ages. Jewish residents were well-integrated into the life and commerce of these towns. For a brief time, antisemitic laws were less rigorously enforced in Obel-olm than in neighboring large cities such as Mainz and Frankfurt. During those years, a few Jewish residents of these cities sent their children to live with "country cousins" in Ober-olm, hoping that their children would be able to continue to attend school and live undisturbed. But as antisemitic laws became more harsh. For example, when Jews were no longer permitted to have checking accounts to conduct business, Jewish residents were not able to make a living and suffered greatly.

Some Jewish residents of Ober-olm were fortunate to be able to obtain visas for the United States and were able to emigrate to safety. Others were not so fortunate, and perished as a result.

During the Western Allied invasion of Germany in April 1945, the nearby Luftwaffe Mainz-Finthen airfield was seized by the United States Third Army, and used by the USAAF 354th Fighter Group which flew P-47 Thunderbolts from the aerodrome, designated ALG Y-64, from 8 to 30 April 1945. Acquired for use by the United States Army after the conclusion of the war, the former German Luftwaffe fighter base was named Finthen Army Airfield and has been used by Army aviation units ever since.

Since 1972, Ober-Olm has belonged to the Verbandsgemeinde of Nieder-Olm, whose seat is in the like-named town.