.For the next few years until 1939 the LSSAH provided the honour guard at several of the Nuremberg Rallies, in 1935 took part in the reoccupation of the Saarland and was the vanguard of the March into Austria as part of the Anschluss. The LSSAH then took part in the occupation of the Sudetenland. In March 1939, it was involved in the annexation of Bohemia and Moravia. Soon after this action, the LSSAH had several motorised components attached, including an armoured car platoon and a motorcycle unit, and was redesignated Infanterie-Regiment Leibstandarte SS Adolf Hitler (mot.).

In January 1939, the Leibstandarten-Ball was held at the Berlin Zoo. Sepp Dietrich had organised this high-profile gala for his men, with famous performers Hans Albers, Heinrich George, and Käthe von Nagy. The guest of honor was Heer commander-in-chief, Walther von Brauchitsch.

When Hitler ordered the formation of an SS division in mid 1939, the Leibstandarte was designated to form its own unit, unlike the other Standarten of the SS-Verfügungstruppe (SS-VT) (SS-Standarte Deutschland, SS-Standarte Germania, and SS-Standarte Der Führer). The Polish crisis of October 1939 put these plans on hold, and the LSSAH was ordered to join XIII. Armeekorps, a part of Army Group South which was preparing for the attack on Poland.

During the initial stages of the Invasion of Poland, the LSSAH was attached to the 17.Infanterie-Division and tasked with providing flank protection for the southern pincer. The regiment was involved in several ferocious battles against Polish cavalry brigades attempting to hit the flanks of the German advance. At Pabianice, a town near Lódê, the LSSAH fought off elements of the Polish 28th Infantry Division and the Wolynska Cavalry Brigade in ferocious close combat.

After the success at Pabianice, the LSSAH was shifted to the area near Warsaw and attached to the 4.Panzer-Division under Generaloberst Georg-Hans Reinhardt, where it saw action preventing encircled Polish units from escaping, and repelling several desperate attempts by other Polish troops to break through. The LSSAH had proved itself an effective fighting unit during the campaign, though several Heer Generals had reservations about the high casualties which the LSSAH and the SS-VT units had sustained in combat.

The regiment was shifted to the Dutch border for the launch of Fall Gelb, and was to form the vanguard of the ground advance into the Netherlands, tasked with capturing a vital bridge over the IJssel and linking up with the Fallschirmjäger of Generaloberst Kurt Student's (left) airborne forces, the 7.Flieger-Division and the 22.Luftlande-Infanterie-Division.

The Invasion of France and the Netherlands was launched on 10 May 1940. On that day, the LSSAH covered over 75 km, securing a crossing over the IJssel near Zutphen after discovering that their target bridge had been destroyed. Over the next four days' fighting, the LSSAH covered over 215km, and earned itself dubious fame by accidentally shooting at and seriously wounding Generaloberst Student near Amsterdam. After the surrender of the Netherlands on 14 May, the regiment was used to form part of the reserve for Army Group B.

After the British armoured counterattack at Arras, the LSSAH, along with the SS-Verfügungs-Division was moved to the front lines to hold the perimeter around Dunkirk and reduce the size of the pocket containing the encircled British Expeditionary Force and French forces. Near Wormhoudt, the LSSAH ignored Hitler's orders for the advance to halt and continued the attack, suppressing the British artillery positions on the Wattenberg Heights. During this battle the regiment suffered heavy casualties.

After the attack, elements of LSSAH's II.Battalion, under the command of SS-Hauptsturmführer Wilhelm Mohnke (right), were mistakenly informed that their divisional commander Sepp Dietrich had been killed in the fighting. In what is known as the Wormhoudt massacre, about 80 British POWs of 2nd Battalion of the Royal Warwickshire Regiment were murdered in retaliation for the supposed death of Dietrich. Although it is unarguable that the massacre occurred, Mohnke's level of involvement is impossible to know, and as such he was never brought to trial.

However the tragic events at Wormhoudt reveal how much the men of LSSAH were politically indoctrinated to form an excellent fighting machine and disregarded the established military code of conduct. The regiment ended the campaign on the coast near Dunkirk, would be admitted.