The occupation commenced with Imperial Japanese Army landings at Padang Pak Amat beach Kota Bharu just after midnight on 8 December 1941, triggering a ferocious battle with the British Indian Army an hour before the attack on Pearl Harbor. This battle marked the official start of the Pacific War and the start of the Japanese occupation of Malaya. Kota Bharu airport was occupied in the morning. Sungai Patani, Butterworth, and Alor Star airports were captured on 9 December 1941. Japanese soldiers landing at Kota Bharu divided into two separate forces, with one moving down the east coast towards Kuantan, and the other southwards towards the Perak River. On 11 December 1941, the Japanese started bombing Penang. Jitra and then Alor Star fell into Japanese hands on 12 December 1941. The British had to retreat to the south. On 16 December 1941, the British left Penang to the Japanese, who occupied it on 19 December.

The Japanese continued to advance southwards, capturing Ipoh on 26 December. Fierce resistance to Japanese progress in the Battle of Kampar lasted three days and three nights between 30 December 1941 and 2 January 1942, before the British had to retreat once again. On 7 January 1942, two brigades of the 11th Indian Infantry Division were defeated in the Battle of Slim River, giving the Japanese army easy passage to Kuala Lumpur, the capital of Malaya. On 9 January, the British position was becoming more desperate and the ABDACOM Supreme Commander, General Wavell, decided to withdraw all the British and Commonwealth forces south to Johor, thus abandoning Kuala Lumpur (which was captured by the Japanese on 13 January).