The table, measuring 18.4m, will form a gathering spot for families, community groups, conservation volunteers and schools.
The table and benches are built from a tree that came down in the park during high winds a few years ago and seats up to 80 people.
The seats and table top are made entirely from Low's Fir, constructed on site by Greenspace Designs which has made other furniture at Lily Hill Park.
The project was part funded by Bracknell Conservation Volunteers, which said the log would have been left to rot if not turned into a table.
Councillor Iain McCracken said: "The picnic table is a wonderful resource for our community, taking a whole class of children for outdoor learning."
Lily Hill Park was restored to its former glory between 2003 and 2008 thanks to a Heritage Lottery Grant.