The 4.5-inch LTE-enabled smartphone arrives in staggered launch dates throughout July.
The Un-carrier and its no-contract brand will carry an entry-level LG Optimus handset each, aimed at wallet-conscious customers.
The carrier now offers the new S5 for the full contract-free price of $649.
The no-contract carrier adds Samsung's latest smartphone to its Android portfolio.
It's ahead of schedule in migrating customers from the MetroPCS and plans to decommission the old network in Boston, Philadelphia, and Las Vegas by the end of the year.
Available first on T-Mobile's network, these mid-and entry-level Android phones make the move to Metro.
The prepaid carrier's latest is a 4G LTE Android that can withstand water, drops, and dust.
The LG Spirit 4G is a prepaid dual-core handset from MetroPCS that packs a 4.5-inch screen, a 5-megapixel camera, and runs on Android 4.0 Ice Cream Sandwich.
Priced at $50, the LG Optimus L70 is one of the best 4G Android handsets on any prepaid network.
T-Mobile and MetroPCS want to move quickly to capitalize on any uncertainty in the prepaid market caused by AT&T's looming acquisition of rival prepaid business Leap Wireless.