The deal is expected to be similar to the three-year, $12 million offer that the former 49ers running back received Sunday from the Eagles, a source told ESPN NFL Insider Adam Schefter.
Gore's contract with Indianapolis also includes $8.5 million in guaranteed money, the source said.
The Colts also will host free-agent receiver Andre Johnson, who was released Monday by the Houston Texans, on Tuesday night, a source told Schefter.
Gore's deal with Indianapolis marks the end of an eventful week for the 31-year-old running back, who intended to sign with Philadelphia over the weekend before reportedly reversing his decision Monday.
The reversal left the Eagles in search of a running back after already agreeing to trade LeSean McCoy to the Buffalo Bills.
Gore is coming off four straight 1,000-yard rushing seasons and has rushed for over 1,000 yards in eight of the past nine seasons. The only season over the past nine in which he failed to reach that threshold was 2010, when he missed five games with a broken hip. Gore is considered an excellent pass protector as well.
A five-time Pro Bowler, Gore was a big proponent of Jim Harbaugh returning to the Niners, who instead "mutually" parted ways with the coach and promoted defensive line coach Jim Tomsula to the head-coach position. Gore said he wanted to see what the 49ers did with the job before deciding his own future.
ESPN's Adam Schefter contributed to this report.
Gore Expected To Sign With Colts
Adam Schefter discusses the report that RB Frank Gore plans to sign with the Indianapolis Colts. Schefter also talks about WR Andre Johnson's plans to visit the Colts.