Berlin had already announced last May its first increase in troop count since the Cold War, but the ministry said it was further revising numbers upwards.
The Bundeswehr (German military) is now expected to grow by 20,000 soldiers to a total of 198,000 in 2024.
Additionally, the number of civilian staff would reach 61,000 over the same period, said the ministry.
"The Bundeswehr has rarely been as necessary as it is now," said Defence Minister Ursula von der Leyen.
"Be it in the fight against Isis terrorism, in the stabilization of Mali, the ongoing support of Afghanistan and against people smugglers in the Mediterranean and the Aegean or with our increased presence for NATO in the Baltics," she said.
Over recent years, the army had seen a significant reduction in troop numbers following Germany's reunification and the end of the Cold War.
In 1990, the number of soldiers reached 585,000, before falling to a low of 166,500 last June.
Washington has repeatedly pressed Germany to increase its defence spending to reach the NATO agreed level of two percent of economic output.
So far, of the 28 NATO members, only the United States, Britain, Poland, Greece and Estonia have met the two percent target.