Filipe Morais has been handed a one-year contract with St Johnstone after a successful trial spell.
The 23-year-old midfielder, who spent a stint on loan with Saints in 2007, joins permanently ahead of the new SPL season.
Morais became available as a free agent after turning down the offer of a new deal with Inverness, who were relegated from Scotland's top-flight last term.
Manager Derek McInnes knows the Portuguese well, having played alongside him at Millwall.
Morais came through the ranks at Chelsea and also had a loan spell at MK Dons before joining the Lions.
After a brief stint with Saints, he moved to Hibernian in 2007, only to fall out of favour at the start of his second season with the SPL club.
Morais was fined at Edinburgh Sheriff Court for an assault at an Edinburgh casino and eventually left Easter Road for Inverness in January along with midfielder Thierry Gatheussi.
Meanwhile, Saints are sweating over the fitness of captain Kevin Rutkiewicz, who suffered suspected knee ligament damage in last night's friendly with Cowdenbeath.