First and foremost, it should be admitted that Polish citizenship can be obtained by marriage on the basis of article 30 paragraph 1 (2a) of the Law on Polish Citizenship. However, one cannot get the citizenship immediately after marriage. The first step for a person wishing to be granted Polish citizenship on the basis of marriage is to settle in Poland with his/her Polish spouse getting at first a temporary residence permit. It should be noted that the place of the marriage conclusion is not important in accordance with the above-mentioned law. However, the marriage is to be recognized by Polish legal norms (i.e. some types of marriages such us, for instance, same-sex marriages are considered illegal in the Polish legal order, and will not be recognized). You should start the process of recognition by filing a standard list of the documents to the competent administrative body (Urząd). These documents include a filled-in application form, a marriage certificate issued no later than 3 months prior to the application, a copy of your spouse’s document proving his or her citizenship, a document showing that you are living together in Poland (for example, a contract for renting a flat signed by both of you). Besides, you might be required to submit some additional document depending on particular circumstances of your case. You should know that the competent authorities will likely check whether you indeed have an intention to reside together with your spouse to be sure that you have not created a fake marriage just for getting a permission to settle in Poland. The temporary residence permit is given for the term no longer than 3 year
Being married to a Polish spouse for at least three years and residing in Poland for at least two years on the basis of a temporary resident permit you are entitled to obtain a permanent residence permit (the rule is enshrined in article 195 paragraph 1(4) of the Polish Law on Foreigners). You should take into account that in such a case the ground of your temporary residence permit matters. The most common situation takes place when you apply for a permanent residence permit on the basis of marriage having a trp on exactly the same ground. But if you have a trp as a refugee or enjoy a subsidiary protection, or have a trp on humanitarian reasons, you are also free to apply for the permanent residence permit on the ground of marriage. However, if you possess a trp on the ground of studies or work and are at the same time married to a Polish citizen, you cannot apply for the permanent residence on the ground of marriage. Apart from that, you should not forget that for getting the permanent residence status your stay in Poland should be consistent. Any long interruptions in your stay are not allowed: you must not leave the country for more than 6 months as a single leave and for longer than 10 months in total.
After all the previously described steps have been successfully completed, you may apply for Polish citizenship on the ground of marriage. The citizenship on the basis of marriage is given to those being married to a Polish citizen for at least three years and residing in Poland for at least 2 years on the ground of their permanent residence permit. The requirements for a continuous and non-interrupted character of your stay in Poland are the same as in case of your permanent residence permit. Apart from that, in order to obtain Polish citizenship, Polish Laws set the requirement of having a certificate of Polish language proficiency (the required level is B1). It means that you should pass a special exam checking your level of language proficiency.
Summing up, it takes at least 4 years of your stay in Poland on the ground of marriage to finally get the citizenship on the mentioned basis. In fact, the whole process takes longer bearing in mind the duration of the formal process of granting a temporary residence permit and, later, a permanent residence permit. Anyway, that seems to be one of the quickest ways of getting Polish citizenship, if you don’t have any other vivid connection with Poland.