Kangwa was part of Chipolopolo’s 2012 African Nations Cup-winning team and had been linked with the Buccaneers for a while.
The Zambian striker is set to replace Collins Mbesuma, whose future at Pirates is hanging in the balance.
Kangwa had unsuccessful trials with Bidvest Wits at the beginning of last season and he also spent six months with Spanish side Recreativo Huelva, but could not secure a contract.
The 19-year-old Kangwa is highly rated in Zambia and was contracted to Nkana FC in the Zambia Premier League before his move to the Sea Robbers.
This is not the first time the former Under-20 Cosafa Player-of-the-Tournament has signed a deal with the Buccaneers. Three seasons ago he also signed, but never got as far as joining them.
Meanwhile, Bucs are set to extend Siyabonga Sangweni’s contract, which expires at the end of the month. There has been a cloud of secrecy around the deal, as the defender was linked with a possible move to Premiership champions Mamelodi Sundowns.