Basis of Presentation and Consolidation and Significant Accounting Policies (Policies)	3 Months Ended
Mar. 31, 2025
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”), and applicable rules and regulations of the U.S. Securities and Exchange Commission (the “SEC”), regarding interim financial reporting. Certain information and note disclosures normally included in the financial statements prepared in accordance with U.S. GAAP have been condensed or omitted pursuant to such rules and regulations. As such, the information included in this report should be read in conjunction with the consolidated financial statements and accompanying notes included in the Annual Report on Form 10-K for the year ended December 31, 2024 (the “2024 Annual Report”). The December 31, 2024 condensed consolidated balance sheet data included in this report were derived from the audited financial statements in the 2024 Annual Report. The accompanying unaudited condensed consolidated financial statements reflect all normal recurring adjustments that are necessary to present fairly the results for the interim periods presented. Interim results are not necessarily indicative of the results for the year ending December 31, 2025.
Principles of Consolidation	Principles of Consolidation The unaudited condensed consolidated financial statements include the accounts of Zai Lab Limited and its subsidiaries, which are wholly owned. All intercompany transactions and balances are eliminated upon consolidation.
Use of Estimates	Use of Estimates The preparation of the unaudited condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates, judgments, and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the period. Areas where management uses subjective judgment include, but are not limited to, accrual of rebates, recognition of research and development expenses based on the Company’s estimates of the actual services performed by the CROs and CMOs, fair value of share-based compensation expenses, recoverability of deferred tax assets, and useful life of intangible assets for commercial products. These estimates, judgments, and assumptions can affect the reported amounts of assets and liabilities as of the date of the financial statements as well as the reported amounts of revenues and expenses during the periods presented. Actual results could differ from these estimates.
Fair Value Measurements	Fair Value Measurements Financial instruments of the Company primarily include cash and cash equivalents, current restricted cash, short-term investments, accounts receivable, notes receivable, prepayments and other current assets, non-current restricted cash, accounts payable, short-term debt, and other current liabilities. As of March 31, 2025 and December 31, 2024, the carrying values of cash and cash equivalents, current restricted cash, short-term investments, accounts receivable, prepayments and other current assets, accounts payable, short-term debt, and other current liabilities approximated their fair value due to the short-term maturity of these instruments, and the carrying value of notes receivable and non-current restricted cash approximated their fair value based on the assessment of the ability to recover these amounts.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Recently Issued Accounting Pronouncements Not Yet Adopted In December 2023, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2023-09, Improvements to Income Tax Disclosures (Topic 740). This ASU requires disaggregated information about a reporting entity’s effective tax rate reconciliation as well as additional information on income taxes paid. This ASU is effective on a prospective basis for annual periods beginning after December 15, 2024. Early adoption is permitted. This ASU will result in additional disclosure in the consolidated financial statements, once adopted. The Company is currently evaluating the impact of this ASU and expects to adopt it for the year ending December 31, 2025. In November 2024, the FASB issued ASU No. 2024-03, Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses. This ASU requires disclosure in the notes to financial statements of specified information about certain costs and expenses. This ASU will be effective for annual reporting periods beginning after December 15, 2026 and interim reporting periods beginning after December 15, 2027. Early adoption is permitted. The Company is currently evaluating the impact of this ASU and expects to adopt it for the year ending December 31, 2027. For additional information on the Company’s significant accounting policies, refer to the notes to the consolidated financial statements in the 2024 Annual Report.

Basis of Presentation and Consolidation and Significant Accounting Policies (Policies)

3 Months Ended

Mar. 31, 2025

The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”), and applicable rules and regulations of the U.S. Securities and Exchange Commission (the “SEC”), regarding interim financial reporting. Certain information and note disclosures normally included in the financial statements prepared in accordance with U.S. GAAP have been condensed or omitted pursuant to such rules and regulations. As such, the information included in this report should be read in conjunction with the consolidated financial statements and accompanying notes included in the Annual Report on Form 10-K for the year ended December 31, 2024 (the “2024 Annual Report”). The December 31, 2024 condensed consolidated balance sheet data included in this report were derived from the audited financial statements in the 2024 Annual Report.

The accompanying unaudited condensed consolidated financial statements reflect all normal recurring adjustments that are necessary to present fairly the results for the interim periods presented. Interim results are not necessarily indicative of the results for the year ending December 31, 2025.

Principles of Consolidation

Principles of Consolidation The unaudited condensed consolidated financial statements include the accounts of Zai Lab Limited and its subsidiaries, which are wholly owned. All intercompany transactions and balances are eliminated upon consolidation.

Use of Estimates

Use of Estimates The preparation of the unaudited condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates, judgments, and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the period. Areas where management uses subjective judgment include, but are not limited to, accrual of rebates, recognition of research and development expenses based on the Company’s estimates of the actual services performed by the CROs and CMOs, fair value of share-based compensation expenses, recoverability of deferred tax assets, and useful life of intangible assets for commercial products. These estimates, judgments, and assumptions can affect the reported amounts of assets and liabilities as of the date of the financial statements as well as the reported amounts of revenues and expenses during the periods presented. Actual results could differ from these estimates.

Fair Value Measurements

Financial instruments of the Company primarily include cash and cash equivalents, current restricted cash, short-term investments, accounts receivable, notes receivable, prepayments and other current assets, non-current restricted cash, accounts payable, short-term debt, and other current liabilities. As of March 31, 2025 and December 31, 2024, the carrying values of cash and cash equivalents, current restricted cash, short-term investments, accounts receivable, prepayments and

other current assets, accounts payable, short-term debt, and other current liabilities approximated their fair value due to the short-term maturity of these instruments, and the carrying value of notes receivable and non-current restricted cash approximated their fair value based on the assessment of the ability to recover these amounts.

Recent Accounting Pronouncements

Recently Issued Accounting Pronouncements Not Yet Adopted

In December 2023, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2023-09, Improvements to Income Tax Disclosures (Topic 740). This ASU requires disaggregated information about a reporting entity’s effective tax rate reconciliation as well as additional information on income taxes paid. This ASU is effective on a prospective basis for annual periods beginning after December 15, 2024. Early adoption is permitted. This ASU will result in additional disclosure in the consolidated financial statements, once adopted. The Company is currently evaluating the impact of this ASU and expects to adopt it for the year ending December 31, 2025.

In November 2024, the FASB issued ASU No. 2024-03, Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses. This ASU requires disclosure in the notes to financial statements of specified information about certain costs and expenses. This ASU will be effective for annual reporting periods beginning after December 15, 2026 and interim reporting periods beginning after December 15, 2027. Early adoption is permitted. The Company is currently evaluating the impact of this ASU and expects to adopt it for the year ending December 31, 2027.

For additional information on the Company’s significant accounting policies, refer to the notes to the consolidated financial statements in the 2024 Annual Report.