DOD leaders are expected to allow iPhones onto the network sometime in May, Reuters reports.
It remains unclear whether the department's employees will be allowed to use smartphones on classified and unclassified networks, or be limited to unclassified portions of the system.
But the decision ends the department's ban on using such devices on official networks.
DOD officials were initially wary of allowing Android systems into Pentagon networks.
An August 2011 review of smartphone operating systems by software security firm McAffee ranked the Android as being the smartphone most susceptible to malware, beating out the iPhone and other similar models.
That said, each Blackberry or Android smartphone being used by the DOD will have to undergo a vetting process, to see if there are any security vulnerabilities either on the smartphones or operating systems running the devices.
The decision comes as Army leaders are preparing to send a new battlefield communication system, based on the Android operating system, into Afghanistan.
Two brigade combat teams with the Army's 10th Mountain Division will take the system, known as "Capability Set 13," into combat when the units depart for Afghanistan later this year.
"This is much needed in Afghanistan," Brig. Gen. Walter E. Piatt, 10th Mountain's deputy commanding general for support, said in an Army statement in March.
Capability Set 13 includes a new version of the Army communications, command and control system known as Nett Warrior.
This version of the system is centered around what the service is calling an "end user device," which is essentially an Android or iPhone-like smartphone that runs off the military's Joint Tactical Radio System.
While the device is based on commercially-available products, the final versions being sent to battle with 10th Mountain have been hardened to military specifications and run off of secure DOD networks.
The new Android-based Nett Warrior system received scathing reviews by active duty soldiers during initial tests in November 2011.
The Army tested two "apps" during those initial trials.
One was a tracking system designed to locate friendly forces on the battlefield and the other was a digital interpreter so soldiers can communicate with locals in Iraq and Afghanistan.
Both apps failed to make the cut.
Troops who were standing next to each other showed up kilometers apart from each other on Nett Warrior during the tests.
The digital interpreter app did not recognize specific dialects and slang words used in rural Afghanistan.
Further, the system's connection to the Army network dropped out repeatedly, leaving soldiers out of contact from other parts of the unit.
When Nett Warrior was online the bandwidth was so restricted that soldiers had to wait minutes before the apps would start working.
The Army claims those initial problems have been resolved and Nett Warrior is ready for prime time.