Based on the folklore by elders in Sabak Bernam, the Sabak Bernam name is derived from the word 'Sahabat Berenam' (Six Companions). According to the story, it was known that there were a company of six (6) brothers who had gone to the upper reaches of the Bernam River and found a log that had fallen and blocked the path of the river. They had decided to cut the log themselves in order to proceed their journey upstream. Although the validity of this story cannot be proven, there is some evidence related to the six companions in the form of graves that are said to still exist to this day, namely within the areas known as keramat (sacred shrines) as follows:

All six were believed to have died in different locations within Sabak Bernam. There are opinion that states they died in Ulu Bernam, Pantai Landu, Seberang Kota, Sungai Langatau Tanjung Medan, Keranji and Pantai Kampung Kemboja. The reason of their arrival is unknown. The one who arrived in Keranji was considered a hero by the villagers as he aided them against the Acehnese raiding Keranji.

According to another story, the Sabak Bernam name was derived from an event in 1880, where six (6) people consisting of former nobilities from Aceh and Sumatra had left their respective homelands and came to Malaya. The six nobles were believed to have fled from the wars occurring in their country. They had plotted to cross the Straits of Malacca and entered the confluence of an unnamed river. The river was later named Sungai Bernam after the six (6) leaders who participated in the journey.

They had then journeyed further upriver. In preparation to spend the night, they had found a raised mound like an anthill, which they decided to make huts for shelter. To cook food, they dug a hole in the ground to be used as a stove, which in their language was called "sabak".

Due to such an event, in which cooking of food was carried out using a stove dug out of the ground, is believed to as how the area got its name "Sabak" and the river used as route by the six of them (berenam) was named Sungai Bernam and the place they took up residence was named "Sabak Bernam" As the story continues, this company of six were:

According to another ancient oral history, Sabak Bernam was said to have existed since 1720 in which at that time was under the rule of the Perak Crown Prince called Raja Inu. At the time, the son of Sultan Ibrahim, the second Sultan of Selangor, reigning from 1778 to 1826, named Raja Onus with his family and consort had moved to Sabak Bernam with a close friend named Haji Ali who also brought his family and wife. Raja Onus had chosen to live on the banks of the Sungai Bernam adjacent to the State of Selangor. Raja Onus had five (5) princes namely Raja Hitam, Raja Indut, Raja Mat Aris, Raja Abidin and Raja Nordin.

When Raja Onus died, his eldest son Raja Hitam took over his place with consent from all of his siblings. He chose his residence adjacent to the State of Selangor and founded the town known as Kota Raja Hitam. The place was also once known as Istana Hinggap Sultan Selangor.

Raja Hitam married a woman named Dasimah and bore several princes and princess namely Raja Tahir, Raja Ja'afar, Raja Nuteh, Raja Chik and Raja Enson. Raja Tahir, Raja Ja'afar and Raja Chik had several sons and daughters.

When Raja Hitam replaced Raja Onus, Raja Hitam had appointed his brother Raja Indut as magistrate for trial cases. During the administration of Raja Hitam, the British Resident of Selangor State had persuaded Raja Hitam several times to allow Sabak Bernam to be placed under British administration in Selangor, but this request was rejected by Raja Hitam.

The British did not give up and had sent an officer named Mr. Roger to persuade Raja Hitam by pledging benefits for Raja Hitam's descendents in the future. Raja Hitam had finally consulted his siblings and had agreed to place Sabak Bernam under British administration in Selangor. The British Resident of Selangor had given a sealed letter which provided guarantees to all heirs of Raja Hitam.

After Sabak Bernam was placed under the governance of the State of Selangor, in 1876, in a letter dated 13 August, the British Resident of Selangor named Captain Bloomfield Douglas had written a letter to Raja Hitam which reads as follows:

"Letter from Captain Bloomfield Douglas the British Resident of Selangor to Raja Hitam, son of Al-Marhum Raja Yunus in Sabak Bernam dated 13 August 1876 on the new rules to hold a white officer Edward Neubroner to hold the post of Collector of Land Revenue Magistrate Police of Sabak Bernam."

With the receipt of the letter, the reign of Raja Hitam in Sabak Bernam had ended. During the reign of Edward Neubroner, he had built the Government Office and a police station staffed by a total of two (2) officers initially.

Once Sabak Bernam was placed under the governance of Selangor State, this marked the beginning for migration of other ethnic groups such as English, Chinese and Indians into Sabak Bernam. The English had opened lands to be turned into estates such as Torkington Estate, Rajah Hitam Estate, Sungai Bernam Estate and Bagan Terap Estate. They used Indian labourers brought in from India. Among the Chinese, those who lived in town had opened business premises such as shops selling beverages (coffee and tea), and had also engaged in selling clothing and grocery goods. There were also among them those who resided by riversides and sea coasts and became fishermen.

Originally, the Sabak Bernam District only covered the area from the northern part bordering Kampung Kota (Perak) to Sungai Nibung area. At present, the area covered is up to Sungai Burong, Sekinchan. The total area of Sabak Bernam District is 99.714 hectares. In the past, Sabak Bernam only covered four (4) but now five (5) sub-districts (Mukim) namely Sabak, Bagan Nahkoda Omar/Sungai Air Tawar, Sungai Panjang, Pancang Bedena and Pasir Panjang.

The district administrative centre since 1970 is in Sungai Besar. During its initial stage, Sabak Bernam was a sub-district to the larger Kuala Selangor District and the administration centre was located in the Sabak Sub-district in today's Sabak Bernam Town area. The relocation of the district administration headquarters to Sungai Besar was due to the old Sabak Bernam Town being often flooded during high tide of Bernam River. This is due to the location of the area near a major river of the area.

When Sabak Bernam was a sub-district under Kuala Selangor, the distance to Kuala Selangor was 40 miles away. In the past, there were no road facilities connecting the two areas. The residents merely used a shortcut which was by land known as burnt land route for the purpose of communication between regions.

Due to the great distance between the District Headquarters and Sabak Bernam District, in 1954, the residents of Sabak Bernam led by the Yang Dipertua (President) of the Sabak Bernam District Malay Association held a special meeting which was attended by all ethnic leaders to discuss difficulties experienced by the residents of this district from various fields.

The outcome of this meeting was an agreement to submit a Memorandum and present it to His Royal Highness the Sultan of Selangor, requesting that Sabak Bernam be made the Seventh District of Selangor. The meeting was also attended by Dato' Onn bin Ja'afar who at the time held the position pertaining to Domestic Affairs, and was also attended by Y.M. Raja Ayub bin Raja Haji Bot and Mr. K.V. Thaver, both of them members of the Selangor State Legislative Council. The meeting was held at the Sabak Bernam Malay Association building.

In terms of economic development, almost 50 percent of the land in the district of Sabak Bernam was used for agricultural purposes, namely coconut, rice, oil palm, cocoa, vegetables and fruits. The main crops generated into sources of income were rice, coconut and cocoa.

The community of Sabak Bernam comprises Malays of Javanese, Banjar and Malay Bugis descent. They consist of different Malay communities with their own dialects and customs. When studied, there were slight demographic specialisations among the different groups. For example, in Kampung Batu 40 and Kampung Sungai Panjang, most of the residents are of Bugis and Javanese descent. In the past, there was an area called Kampong Sungai Bugis as many of its residents were of Bugis descent.