Coverage of the Wembley final, including pre-match build up and post-match analysis, pulled in a 38.7% share of the audience for BBC One between 12.40pm and 5.30pm.
The absence of a big club in the final, and the presence of Cardiff City from outside the Premier League, led to the lack of interest among viewers.
The BBC is considered to have done a good job of building up interest in the competition, with the last three finals all averaging more than 9m viewers, from a low of 6.3m in 2004.
The final was the last FA Cup match on the BBC before broadcast rights, which also include England internationals, switch to ITV and Setanta Sports in August, as part of a £425m four-year deal.
From next season, ITV will bill itself as the free-to-air home of live football, having also retained the Champions League for another three years by paying £160m to secure live rights.
Elsewhere, the sixth episode of ITV1's smash hit 'Britain's Got Talent' pulled in a chunky 8.6m viewers and a 37.3% share between 8pm-9pm on Saturday.
However, ITV1's decision to air quirky, offbeat US drama 'Pushing Daisies' in a prime time slot on Saturday has not paid off, as it continues to shed viewers from the opening night's 5.7m.
Saturday's sixth episode of the eight-part series brought just 2.7m viewers and a 12.6% share from 9pm-10pm.
On Sunday, BBC One capitalised on the hype ahead of this week's cinema release of the hotly anticipated 'Indiana Jones and the Kingdom of the Crystal Skull', starring Harrison Ford, by dusting down the third instalment in the series for viewers, almost 20 years after its cinema release.
'Indiana Jones and the Last Crusade' pulled in a whip-cracking 7.3m viewers and a 30.7% share between 8pm-10pm, which bodes well for the fourth instalment as it gets set to hit cinemas on Friday.
Channel 4 showed the critically acclaimed Hollywood movie 'Brokeback Mountain', starring Jake Gyllenhaal and the late Heath Ledger, in the 9pm-11.35pm slot. It had 1.8m viewers and a 9.9% share, while Channel 4+1 added 82,000 viewers and a 0.7% share of the multichannel audience.
ITV1 had a dismal night, with Ross Kemp action drama 'Ultimate Force' getting just 3.5m viewers and a 15.3% share between 9pm-10.30pm.
Earlier in the evening, ITV1's long running village-set drama 'Heartbeat' earned 5.8m viewers and a 24.8% share from 8pm-9pm.