The 32-year-old has signed until the end of the season, subject to international clearance, and will arrive in Scotland in the “next few days”.
Kawashima first emerged as a signing target almost two months ago, but had to go through a lengthy work permit application, which included taking an English exam in Japan.
Reports recently claimed that Dutch club NEC Nijmegen could hijack the deal, but United have announced the end of the saga.
Kawashima has 72 caps for Japan and played at the last two World Cups. He was a free agent after leaving Standard Liege in the summer.
In a statement released by the club, Kawashima said: “Finally I’m able to join to Dundee United. I’m delighted to join this club.
“I will try to do all my best with my fighting spirit and my ambition as a player. I hope that can bring something different to the squad and also I hope I can use my experience as well. I’m looking forward to wearing the Dundee United jersey on the pitch soon.”
Manager Mixu Paatelainen added: “It has taken a bit longer than any of us would have liked but this is a fantastic coup for the club.
“Eiji will strengthen the competition in the goalkeeper’s position. He is a seasoned professional who has played at major tournaments and this experience will help our young goalkeepers also.
“He is a strong character who has shown great desire to play for Dundee United and I look forward to working with him.”