The deal is for the veteran's minimum exception of $2.6 million, sources told ESPN's Bobby Marks.
Howard's decision came just over an hour after he tweeted and deleted a message that made it appear as though he was returning to the Los Angeles Lakers.
Charania then reported Howard was continuing to "consider all of his options."
Howard believed there was a one-year, $3-million offer on the table from the Lakers when he posted his tweet, sources told Yahoo's Chris Haynes. However, the team is reportedly adamant no formal offer was made, and the number represented a "deal concept."
Philadelphia will be Howard's seventh NBA address. The veteran big man averaged 7.5 points, 7.7 rebounds, and 1.1 blocks last season in a reserve role with the Lakers, winning his first championship.