In May 1970 Boland resigned from the government. He sympathised with Neil Blaney and Charles Haughey who were dismissed from the government because of a plot to import arms into the country. Later that year he resigned from Fianna Fáil and resigned from his Dáil seat. He remained outspoken in his views on Northern Ireland. He went on to form his own political party, named Aontacht Éireann. The party failed to win electoral support.
Boland will be infamously remembered for interrupting a speech by Dr. Patrick Hillery at the 1971 Fianna Fáil Ard-Fheis. Boland and his supporters caused chaos in the hall. RTÉ cameras filmed a live power struggle in the Fianna Fáil party. When his supporters started chanting 'We want Boland', Hillery famously replied, 'You can have Boland, but you can't have Fianna Fáil'.
Kevin Boland died in Dublin in 2001.