Eickhoff elected free agency Oct. 6.
The Pirates outrighted Eickhoff to Triple-A Indianapolis on Sunday after he cleared waivers.
Eickhoff was designated for assignment by the Pirates on Friday.
Eickhoff (0-1) allowed 10 earned runs on 10 hits and one walk while striking out four across 4.1 innings to take the loss Wednesday against the Cubs.
The Pirates selected Eickhoff's contract from Triple-A Indianapolis ahead of his scheduled start Wednesday against the Cubs.
Manager Derek Shelton said Eickhoff will be called up from Triple-A Indianapolis to start Wednesday's game against the Cubs, Rob Biertempfel of The Athletic reports.
Eickhoff was called up from Triple-A Indianapolis on Tuesday, Jason Mackey of the Pittsburgh Post-Gazette reports.
The Pirates reassigned Eickhoff to minor-league camp Tuesday.
Eickhoff signed a minor-league deal with the Pirates on Monday, Robert Murray of FanSided.com reports.
The Mets outrighted Eickhoff to Triple-A Syracuse on Friday.