When he acceded the throne, the Chola Empire was at its peak stretching from Southern India to Vengai(Bengal) to parts of Southeast Asia.

Rajendra's forces were victorious in the Battle of Kudal-Sangamam leading to greater Chola influence in the Krishna river.

he also helped his father conquer the kingdoms of Polonnaruwa and Ruhuna bringing all of Sri Lanka under Chola rule.

[6] Since he ascended the throne during a time of war, Jayamkondar's Kalingattuparani describes him as "The one who wore the crown on the big battlefield.

A Chalukyan account of the battle is only found in a later inscription dated c. 1071, which recounts this incident after a gap of almost 15 years and which only mentions the death of Rajadhiraja.

During this time, the Tamil trading guilds Thisaiayiratthu Annuruvar tarded in Anuradhapura further increased their activities in the Island.

Vijayabahu established himself in Wakirigala and organized his army for a fresh attempt to capture Polonnaruwa, however this failed and his troops were defeater by Rajendra's son Uttama.

[10] The Chola forces were in battle with the Chalukyan army at Koppam (Koppal) located on the Tungabhadra River in 1053–54 AD.

Even Rajendra-II had been injured initially and had withdrawn from the battle, but he came back and turned the tables on the Ahavamalla (Someshvara-I) who called himself 'Trailokyamalla' – lord of three worlds).

From an inscriptions of his from Manimangalam we understand that at the end of the battle, the Chalukyas were defeated and a number of officers of their army lay dead on the field.

"While the army of his elder brother was at {his) back, the king(who wielded) the sceptre {and) tfas embraced by {the golldess of) Prosperity, conquered the #seven and a half lakshas of Irattap&di.

(The Icing) seized his elephants and horses, troops of camels, women and treasures,• and anointed himself (in commemoration) of the victory.

Ottakoothar's Vikrama Cholan Ula mentions:[7]The King [Rajendra II] with his one elephant in a fierce war, conquered his enemies in the city of Koppam and took over their thousand elephantsKollapuram is identified with Kolhapur in present-day Maharashtra.

[18] This view is also held by a few other historians who credit the burning of Kalyanapuram, the capital of the Chalukyas and the planting of victory at Kollapuram, again two separate events, to Rajadhiraja Chola I.

Subsequently, Someshwara-I also engaged the Chola army under Rajendra-II and Virarajendra at Kudalasangamam, the result was yet another heavy defeat for the Chalukyan king.

[citation needed] When he was a co-regent of his elder brother, Rajadhiraja Chola I, he shared the latter's workload by taking care of the internal affairs of the state.

For example, he passed a royal order in 1056 CE to provide paddy and other ration to Santi Kuttan Tiruvalan Tirumud Kunran alias Vijaya Rajendra Acharyan(named after Rajadhiraja) for enacting RajaRajeswara Natakam (a musical), in the Brihadeeswarar Temple, Thanjavur.

He alter convinced the residents of to complete the foundational work of the temple and install an Idol of Somaskandar, a form of shiva.

[7] He also issued 120 kalams of paddy Brihadisvara Temple in Thanjavur for an reenactment play known as "Rajarajesvara nata-kam" about the conquests of Rajaraja I.

[24] Other titles conferred on the members of the royal family by the king include Chola-Pandyan, Chola-Gangan, Chola-Ayodhyarajan and Chola-Kanyakubjan.

An inscription in the 10th year of the reign of Rajendra Chola II is found on a menhir in Meppara near Rajkumari, Idukki District, Kerala.