The band will begin releasing nine double A-sided 7" singles each month from mid-August.
The tracks are taken from their 2011 sessions for latest album I'm with You.
Smith explained that the band didn't want the songs to remain hidden forever, and that they were good enough to be heard in some capacity by fans.
"We just wanted them to come out because we just really like them," he told Billboard. "We didn't want them to get lost, so we're gonna put them out, mainly for our fans.
"They would've waited for the Warner Bros box set in, like, 2020, if there's even a record company around then. I'm glad they're going to see the light of day because it's an important part of the band and what we were doing at the time."
'Strange Man' and 'Long Progression' will arrive on August 11, followed by 'Magpies' and 'Victorian Machinery' on September 11.
Smith described new track 'Long Progression' as "kind of a flowing, kind of mid-tempo funk".
Red Hot Chili Peppers will play three big stadium shows this summer, starting at Knebworth Park on June 23. They will then perform at Sunderland's Stadium of Light on June 24 and Dublin's Croke Park on June 26.
Watch the music video for Red Hot Chili Peppers' latest single 'Look Around' below: