The Liverpool-born forward came through the ranks at Boundary Park, and quickly caught the eye of several clubs.
He made 15 appearances for Oldham last season after making his league debut against Millwall in January.
Bolton boss Owen Coyle said: "We're delighted to have him, and we'll gradually take step upon step with him to such a time where he is ready to challenge for a first-team place.
"The fact that he played very well against us [in the pre-season friendly] just cemented what we already knew about Tom, and that he is a young player with great potential making his way in the game."
This lad looks to be a fantastic prospect and with the amount of clubs interested seems like a really good capture for us and definately one for the future
Borgy
Eaves follows Martin Petrov, Robbie Blake, Marcos Alonso and Ivan Klasnic in joining Bolton ahead of the new season.
Oldham chief executive Alan Hardy said: "There has been a great amount of speculation these last few weeks about Tom's future.
"A number of clubs had shown an interest in him, and Tom chose to speak with Bolton last week.
"The negotiations have now been concluded and we are happy with the deal that gives Latics a guaranteed fee plus the usual add-ons and sell-on clause. We wish Tom all the best at the Reebok."
Source: BBC Sport
Source: BBC Sport