Parliament approved the move on Monday.
The Speaker, Lord Fakafanua, said it was crucial the Attorney General became a member of the committee with no casting vote, similar to how the Auditor General was part of the Public Accounts Committee.
He said the committee's work will now be more effective.
Normally the Attorney General is co-opted to provide legal opinion to committees if required.
Ha'apai MP Veivosa Taka said he believes parliament should stick to that routine, calling on the Attorney General.
He said it's the responsibility of committee members to carry out their work themselves.
But Tongatapu MP Siaosi Sovaleni moved the motion saying the Attorney General played an important role explaining the purpose of bills.
Justice Minister Vuna Fa'otusia was also in favor of the motion.