Lom was founded by the Thracians under the name of Artanes in Antiquity. After them the Romans called the fortress and the town Almus, from where the name of the today's city and of the Lom River comes. There are no reports proving that there existed a big settlement in the Middle Ages. It was not until Ottoman rule that it enlarged but for a long time it was under the shadow of the dominant towns of Vidin, Nikopol and Silistra. It is assumed that the Ottoman village was founded in 1695 by Kara Mustafa and Murad Bey, who were defeated at Vienna in 1683 and who came here sailing rafts along the Danube.

The name Lom Palanka was mentioned for the first time in 1704. The settlement then called Palanka stood between village and town in size and importance. In 1798 Lom suffered from brigand raids. With the development of shipping along the Danube after 1830, the importance of the town grew. The road to Sofia contributed to its progress and turned it into a main export port to Vienna (Austria). By 1869 there were 120 shops, 148 trade offices, 175 food shops, 34 coffee bars, six hotels and two mills. The town was centred on the old Kale (fortress), which was entered through three kapii (gates) — Vidinska, Belogradchishka, Sofiyska. The tradesmen from Lom offered goods at the biggest fairs in the region and beyond. In 1880 there were 7,500 inhabitants in the town. Lom is proud of its traditions from the period of the Bulgarian National Revival. During the national revival, the first community centre in Bulgaria (1856) was founded in the town, the first women's society in the country was also established in 1858 and one of the first theatre performances took place in the town. Krastyu Pishurka, a noted educator, also worked in Lom. Until the Second World War it was a major market town. After 1944 the industry developed — sugar factory, can factory, grain industry. It became a port for the northwestern part of Bulgaria.

Neighbourhoods of Lom include: Boruna Humata Kaletata Lyulyatsite Mladenovo Mladost Momin brod Stadiona Zornitsa

Plazha (Bulgarian: Плажа) - the 500 m. long pebbled beach at the bank of the Danube River, 3 km. from the centre of the city Town Museum of History, housed in the building of the old town-hall. Preserved foundations of the antique fortress Almus Postoyanstvo, the oldest community centre in Bulgaria Building of the former School of Pedagogy The Church of Boruna Monument of Tseko Voivoda (1807–1881), a participant in the battles for liberation of Serbia and proclaimed by the Serbian government to be a voyvoda (revolutionary leader)

The majority of the population of Lom is Christian Orthodox. The second biggest religious group is Protestantism-adventists and baptists.

Lom Peak on Livingston Island in the South Shetland Islands, Antarctica is named after Lom.

The municipality of Lom consists of the following 9 villages plus the town of Lom itself, which is the administrative centre of the municipality.

Lom is twinned with: Debar Municipality, Republic of Macedonia Linz, Austria Lom, Norway Niš, Serbia Freiburg im Breisgau, Germany