Kevin Acee of the San Diego Union-Tribune passed along details of the deal.
Ellis is coming off a down year with the Miami Marlins. He posted a lackluster .210/.298/.371 triple-slash line with six home runs while making just 51 appearances as J.T. Realmuto received a lion's share of starts behind the plate for the Fish.
In addition to the sporadic playing time, the 36-year-old Austin Peay State University product told Bob Nightengale of USA Today in July constant rumors about the organization's sale had a negative impact.
"It's tough on guys in here," he said. "You're living on edge. It's especially tough for a lot of these guys who have been lifelong Marlins. This is all they know."
Ellis' best offensive season came with the Los Angeles Dodgers in 2012 when he finished with career-high totals in both homers (13) and OPS (.786) while playing 133 games.
The Missouri native provides limited defensive contributions, as well. He owns a minus-39 defensive runs saved mark across more than 4,700 career innings, per FanGraphs. He also finished last season 10.4 runs below average in pitch-framing metrics, according to StatCorner.
So much of what Ellis brings to the table at this stage of his career falls into the intangible category. He's built a strong rapport working with pitchers during his time with Los Angeles, Miami and the Philadelphia Phillies, and he can also provide veteran leadership in the clubhouse.
He should slot in as a backup after joining the Padres.