The 1st and 2nd Regiments were consolidated, reorganized, and redesignated 1 October 1917 as the 124th Infantry and assigned to the 31st Division, as part of the mobilization for World War I.

[1] In 1920–1921, the 1st Infantry Regiment was reorganized in the Florida National Guard, with the headquarters federally recognized 4 June 1921 at Jacksonville.

In March 1933, Company H guarded Giuseppe Zangara, the would-be assassin of President Franklin D. Roosevelt, before his execution at the Florida State Prison at Raiford.

From 7 to 9 June 1932, Companies A and B were used for guard and security duties in connection with the visit of Cuban national officials to Hollywood, Florida.

In March 1935, elements were used for guard and security duties in connection with the visit of President Roosevelt to Winter Park, Florida.

The regiment was inducted into active federal service at Jacksonville on 24 November 1940, and moved to Camp Blanding, Florida, where it arrived on 18 December 1940.

On 11 January 1942, it moved to Fort Benning, Georgia, where it was used as an additional demonstration unit for the students of the Infantry School.

On 12 October 1943, it departed the Infantry School for Fort Jackson, South Carolina, under the XII and IX Corps, where it was inactivated on 2 March 1944.

The inactivation came as a shock to many in Florida, and the Governor, Spessard Holland, appealed to the Secretary of War that the 124th Infantry be kept in service.

He stated that "Its inactivation would be a severe blow to morale both in and outside the service and arouse bitterness in the hearts of many of our citizens who have served in it in the past".

The 124th Infantry performed their first annual field training since reorganization at Fort Jackson from 18 July 18 to 1 August 1948.

On 26 December 2002, both 3rd and 2nd Battalions, 124th Infantry, were ordered into active federal service in support of the "War on Terror."

Ordered into active federal service 2–16 January 2003 at home stations; On the night of 19 March 2003, soldiers of C Company, 2nd Battalion, 124th Infantry, positioned in Jordan and both A and C Company, 3rd Battalion, 124th Infantry, positioned in Kuwait, were among the first U.S. soldiers to invade Iraq.

A Silver color metal and enamel device 1 3/16 inches (3.02 cm) in height overall consisting of a shield blazoned: Argent, on a saltire Gules between in chief a Roman sword in sheath paleways point to base and in base a prickly pear cactus, both Vert, a fleur-de-lis of the first.

Attached below and to the sides of the shield a Silver scroll inscribed "FLORIDA AND COUNTRY" in Black letters.