Nueva Ecija was created as a military comandancia in 1777 by Governor General Clavería, with the capital, Josean at Baler (now part of Aurora). It was formerly part of the province of Pampanga. From its beginning, its land area grew to cover almost the entire island of Luzon. Spanish records in the Philippines recognize two Spanish countries in the Pacific-- Las Islas Filipinas and Nueva Écija. Poverty was the only reason why Nueva Ecija was not given recognition as a separate country from the Philippines by the King of Spain in the 1840s. From 1777 to 1917, Nueva Ecija's territory was subdivided to give way to the creation of other provinces. The provinces of Tayabas (now Aurora and Quezon) including Polillo Islands, Palanan (now Isabela), Cagayan, Nueva Vizcaya, the territory which became part of the Province of Quirino, and the province of Manila, north of Tondo, and the District of Morong (now Rizal) were among those created out of Nueva Ecija in 1867.
During World War II Japanese planes invaded the province and Nueva Ecija fell to air raid in December 1941. The Imperial Japanese Army entered the province and Nueva Ecija was taken in 1942. On March 29, 1942, under the leadership of Luis Taruc, the Hukbalahap (Hukbo ng Bayan Laban sa Hapon - People's Army Against the Japanese) was organized in Sitio Bawit, Barrio San Julian in the town of Cabiao. It was perceived to be the military arm of the Partido Komunista ng Pilipinas (Communist Party of the Philippines), that brought about the beginning of the early organized resistance of the Filipino people.
During World War II under the Japanese Occupation, the Philippine Commonwealth Army re-established the Military General Headquarters, Military Bases and Camps in the province of Nueva Ecija from 1942 to 1946. The engagements of the Anti-Japanese Imperial Military Operations in Central Luzon included Nueva Ecija, Pampanga, Tarlac, Zambales, Bulacan and Northern Tayabas (now. Aurora) from 1942 to 1945 and aided the the Hukbalahap Communist guerrillas and the local Filipino troops and officers against the Japanese Imperial forces (1942-1944) and the Allied Liberation (1944-1945).
At the outbreak of the Nueva Ecija Conflict in 1942 to 1944 under the Japanese Occupation, various recognized guerrilla groups and the Hukbalahap communist resistance was main commands of the battle conflicts and insurgencies to side by side in the main province of Nueva Ecija and helping local Filipino troops and military officers under the oncoming 2nd, 21st, 22nd, 23rd, 25th and 26th Infantry Division of the Philippine Commonwealth Army and incoming 2nd Infantry Regiment of the Philippine Constabulary and attacking Japanese Imperial forces and Makapili militia groups. When the end of the Japanese insurgency in Nueva Ecija on 1944, some various recognized guerrilla groups and the Hukbalahap communist resistance was over to retreated by the Japanese troops and Makapili rebels. Before the liberation and re-invading the main province of Nueva Ecija was downfall by recapturing the local Filipino troops of the Philippine Commonwealth Army and Philippine Constabulary on 1944 to 1945 and the American troops of the U.S. Army and the U.S. Army Air Forces on 1945 and help various guerrillas and Hukbalahap communist resistance and defeats Japanese troops and Makapili militias.
In January to August 1945, combined American and Filipino soldiers liberated Nueva Ecija with the recognized guerrillas continuing to harass the Japanese at every opportunity. When Filipino soldiers of the 2nd, 21st, 22nd, 23rd, 25th and 26th Infantry Division of the Philippine Commonwealth Army and the 2nd Infantry Regiment of the Philippine Constabulary was re-invading launches to entering liberated the province of Nueva Ecija and helping recognized guerrilla resistance fighter units, the Hukbalahap Communist guerrillas and the American troops under the United States Army and U.S. Army Air Forces against the Japanese Imperial forces and the Makapili rebel fighters during the Allied Invasion of Nueva Ecija.
On January 30, 1945 American Army Rangers, Alamo scouts and Filipino guerrillas conducted a raid to liberate Allied civilians and prisoners of war in Cabanatuan, and was successful with over 516 rescued. By January 31, 1945, the liberated civilians and POWs reached Talavera. The rescue is commemorated in Talavera.
In 1896, Nueva Ecija became one of the first provinces to revolt against Spanish rule, and one of the provinces which declared its independence in 1898.
In 1946 to 1954, When the Government troops under the Armed Forces of the Philippines was the conflict and insurgency operations from the main invaded the province of Nueva Ecija and they fought against the Hukbalahap Communist rebels and since the Hukbalahap Rebellion under the Cold War.
Nueva Ecija is considered the main rice growing province of the Philippines and the leading producer of onions (Municipality of Bongabon, Nueva Ecija) in the country and in South East Asia. It is currently the 9th richest province in the country.
Nueva Ecija is one of the top producers of agricultural products in the country. Its principal crops is mainly rice but corn and onion are also produced in quantity. The province is often referred to as the “Rice Granary of the Philippines.” Other major crops are onion, mango, calamansi (calamondin orange), banana, garlic, and vegetables. The town of Bongabon at the eastern part of the province at the foot of the Sierra Madre mountains and its neighbouring Laur and Rizal are the major producers of onion and garlic. Bongabon is called the "onion capital of the country". A sunflower farm is also housed inside the Central Luzon State University campus in Science City of Muñoz.
Education is very well established as a major industry in the province. The leading educational institutions are the Central Luzon State University in Munoz and Nueva Ecija University of Science and Technology; Wesleyan University-Philippines, the only internationally-accredited school in Central Luzon; College of the Immaculate Conception; La Fortuna College and Araullo University in Cabanatuan. There are 18 tertiary level institutions in Cabanatuan City alone.
Health services is also a notable industry and a number of hospitals cater to patients from within Nueva Ecija and some coming from neighbouring provinces. There are also a number of schools of nursing and midwifery, mostly in Cabanatuan.
There are poultry farms in a number of towns, most notably, the Lorenzo poultry farms in San Isidro which is one of the largest in the country. Duck raising and egg production is also an important livelihood. Fishponds are unevenly distributed throughout the province but the largest concentrations are in San Antonio, Santa Rosa, and Cuyapo.
Fabrication of tricycle "sidecars" is widespread in the province, notably in Santa Rosa, where prices are as low as PhP 7,000 which is practically the cheapest in the country.
Several areas have mineral deposits. Copper and manganese have been found in General Tinio, Carranglan, and Pantabangan. The upper reaches of Carranglan and Palayan City are said to contain gold.
In June 2008, it has also received the title: "Milk Capital of the Philippines" due to the reason that Nueva Ecija gathers more milk from both cows and carabaos or water buffaloes than any other place in the Philippines. The Philippine Carabao Center is located in CLSU compound in Munoz City.