The 91-year-old completed her treatment at Coventry’s University Hospital, 21 days after she made history earlier this month.
NHS England said at the time the "booster jab" three weeks later would "ensure she has the best chance of being protected against the virus".
Others in the highest priority group who received the Pfizer/BioNTech jab on 8 December, or 'V Day' as it has come to be known as, are due to receive their second dose this week.
Margaret Keenan reunites with her family after the first jab:
It comes as the UK reported its highest number of daily cases, with more than 53,000 new Covid cases reported on Tuesday.
The most recent figures published by the Department of Health showed that the number of people to have had their first vaccination between 8 December and 20 December in the UK was 616,933.
That figure differs to the number quoted by Prime Minister Boris Johnson who, when speaking on Christmas Eve, said almost 800,000 people had been given their first dose of the two-stage vaccine.
The vaccination programme has now been widened to GP led sites and care homes after an initial delay caused by difficulties in transporting and storing the vaccine - which must be kept at ultra-low temperatures.
Professor Andy Hardy, Chief Executive of University Hospitals Coventry and Warwickshire NHS Trust where Ms Keenan received her vaccination, said: "We were delighted to welcome Margaret Keenan back to Coventry’s University Hospital today to safely receive the second dose of the vaccination.
"Our hardworking staff who have been involved in the vaccination programme have remained in contact with Margaret’s family since that day and we are delighted that Margaret has been continuing to recover well at home following her discharge from hospital."
Speaking after having the first jab earlier this month, Ms Keenan said: "Hopefully it’ll help other people come along and do what I did, and try and do the best to get rid of this terrible thing."
The mother-of-two added: "I say go for it, because it’s free and it’s the best thing that’s ever happened. If I can do it; well, so can you."
Prof Harding urged others to "come forward" and receive their vaccination when invited to do so.
People in Wales are to begin receiving their second dose of the vaccine from January 5.